Negative Voltage between Ignition Coil and Battery?

Tiny
ALTHEA MAYBERRY
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  • 1985 DODGE TRUCK
  • 4.2L
  • V8
  • 2WD
  • AUTOMATIC
Dear CarPros,

I have the truck listed above Ram D150 with a 1979 318 cid engine. I have been working on this truck for nearly 3 years now. The person(s) who owned it before me made a mess of things. I have had to do a lot of extensive work on it. Let me explain everything I have done.
I have replaced:
*Distributor and pickup coil (Old distributor had a bent shaft)
*Ignition coil
*Starter relay
*Ignition switch
*ECU and wiring loom
*One bad fusible link in the duck foot wiring loom
*Ballast resistor

I have also replaced some wiring because I moved the ignition coil from the back firewall to the driver-side fender well. However, after investigating everything I have done, with a friend of mine who is a retired ASE-certified mechanic, neither of us can figure out what is wrong.
Where I think I went wrong is with the ECU wiring loom. The only place I could find a new wiring loom was at SummitRacing. Com. Their ECU wiring looms are supposed to be universal and can be installed on a single ballast or a double ballast resistor system. However, the wires are different colors than what is installed in the original wiring. So, I had a bad time of it, figuring out how to wire it. I will include the diagram supplied by SummitRacing. Com.
Now I will tell you what is going on as to what’s preventing it from running. I am getting spark in the start mode since the engine is trying to start. However, it won’t stay running, not even for a second in run mode. We have done some testing with my Volts/Ohms meter, and we are getting -12.5V from the positive side of the ignition coil and the positive side of the battery, with the key on and the key off. I do believe that it’s supposed to read positive 12.5, with the key on, from positive ignition coil to negative battery or any ground. I must have hooked up something backward.

I certainly hope you can help me figure out what I did wrong.

Sincerely,

Althea Mayberry
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Saturday, September 16th, 2023 AT 11:46 AM

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Tiny
CARADIODOC
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First, do not use the battery's positive post for your voltmeter. We do that for some tests when checking if a ground circuit is good, but for the majority of tests using the positive post is only going to add a pile of confusion. For 99 percent of tests, voltages in a circuit are referenced to ground, meaning the battery's negative post or any paint and rust-free point on the frame, body sheet metal, or engine. If you're using a digital voltmeter and you just have the test leads switched, just ignore the minus sign in the displayed reading. For this type of problem, you can get faster results with a simple test light; the old kind with a standard light bulb, not one of the new electronic ones. For the most part here, we're just interested in whether we have something or nothing. The exact voltages are usually not important.

Next, there were two versions of ignition systems that used the small five-pin ignition module. My 1980 Volares use the newer version that only has four pins in the odd-shaped five-pin connector. Older versions used all five pins. The difference is the older style with five pins used the dual ballast resistor. One section of that fed that fifth pin. That dual unit caused a real lot of trouble, so the newer version did away with the troublesome half and just used a single resistor and the four-pin module. If I remember correctly, you can use the four-pin module in a vehicle that has the five-pin connector and dual resistor. Half of that resistor just won't be connected to anything and won't do anything.

The symptom you're describing is exactly what that dual ballast resistor caused. By being burned open, 12 volts did not show up on the one pin in the module, so there was no spark, (to keep the engine running). The clue had to do with the fact that all the way back to the beginning of time, a battery's voltage gets drawn down to as low as 9.6 volts during cranking. When we had breaker points, when they turned on, the only thing in the circuit to limit current was the very small resistance of the ignition coil's primary winding. With such little resistance, the high current would overheat and burn the contact points in a few hundred miles. To prevent that, the ballast resistor was added. The added resistance caused current to be a lot lower, and that made the contact points last thousands of miles.

As the breaker points operate, when they're open, there's no current flow, and 0 volts dropped across the ignition coil. When the points close, there is current flow and there's full system voltage across the coil, (typically around 14 volts, but we use 12 volts for this story). If we could smooth that out and take an average, we'd see roughly 10 volts across the coil.

Now take that lowered voltage due to the resistor, and couple that with the very low battery voltage during cranking, and that average voltage is so low, the very weak spark that results is often not strong enough to jump the spark plug's gap. That results in a crank / no-start, or very hard starting, especially in cold weather. To prevent that, the ballast resistor is bypassed during cranking. That is hard on the breaker points, but only as long as cranking takes place. Once the engine is running, that resistor is switched back into the circuit to protect those points.

The ballast resistor was held over with the world's first electronic ignition system, which was on Dodges in 1972 and Chryslers and Plymouths in '73. GM had their first version, the very nice HEI, (high energy ignition) system in 1976 or late '75.

The need to bypass the resistor was still there with the electronic ignition systems. The big three did that three different ways. GM did it with a "solenoid, ("S") terminal on their starter solenoids. It switched full battery voltage onto the ignition coil during cranking. Ford did it with a similar tap on their starter solenoids that sit on the inner fender next to the battery. They used at least three different versions of that solenoid to be sure there was sufficient confusion and frustration. Chrysler did the switching with a special tap on the ignition switch.

The point of this story is when the engine runs during cranking, but not once you release the ignition switch, it's due to that ballast resistor being burned out, or in this case, possibly not wired correctly. During cranking, the ignition switch is putting battery voltage on the terminal at the ignition module, but when the key is released to the "run" position, that circuit is turned off, but no voltage is coming from the ballast resistor to keep the module powered up.

The clue to this is the engine will run as long as the ignition switch is held in the "crank" position". With your left hand, you can reach over to shift into "drive", then the neutral safety switch will turn off the starter relay and the starter, but the engine will continue running until the key is released. That trick can allow you to drive out of the intersection where this failure occurred most often. Seems to be related to extended idling, as when sitting at a stop light.

I should add that there's one more version of this system that used two pick-up coils in the distributor and a relay to switch between them. I only saw that once, but I don't remember which years or models it was used on. One pickup was for normal running. The second one was switched in only during cranking to provide retarded spark for easier cranking. If you should have two pairs of wires coming out of the distributor, we're going to use just one of them. Either one can be used, but it may be necessary to readjust the ignition timing once the other problems are solved.

It will take me some time to find my diagram for this system. When I do, I'll post it to give us a place to start.
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Saturday, September 16th, 2023 AT 8:06 PM
Tiny
CARADIODOC
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These first two diagrams are right out of the service manual. They can be hard to follow until you become familiar with Chrysler diagrams. The third one is a diagram I drew to simplify the circuit. One point to be aware of is all through the '70s and most of the '80s, everything that had 12 volts switched onto it through the ignition switch used a dark blue wire under the hood. That includes one wire to the alternator, one to the voltage regulator, one to the choke heater, one to the ignition module, and one to the ballast resistor that split into two terminals for the dual resistor in this diagram from 1974. On many of the truck models, they used a red wire instead, so if you see either a red or a dark blue wire. You should find 12 volts on it when the ignition switch is in "run".

I won't whine and snivel if you use a digital voltmeter, but I would strongly suggest using a test light for these tests because they involve unplugging things in some cases. I can explain that better later. Your comment about the fuse link wire is what prompted me to recommend the test light. Also, I forgot to mention there's a sixth connection on the ignition module. That is the case, or housing, must be bolted to the body for the ground connection. Be sure that's tight and not rusty.

I added notes in the fourth diagram. Since the engine runs at times, we know the pick-up coil in the distributor has to be okay. If you needed to check it, best is to go right to the five-pin plug and check from there with an ohm meter. I can help with that, if necessary. I've found them to read around 650 to 700 ohms, but some service literature says it should be a lot lower. For the most part, you want to have something, not an open circuit. You can unplug the pick-up coil and measure there, but by doing it at the 5-pin connector, you're including the wires and the 2-pin connector terminals in the test. Next, with that 5-pin connector unplugged, you should find 12 volts on the other three terminals, (two if that's all you have). If one of those is missing, the ballast resistor is the likely suspect.

Now to add a clinker to the works, I see a reference to the starter relay and the wire from the ballast resistor. I haven't searched for that yet, but it is possible one of those ignition module wires gets its 12 volts from the starter relay during engine cranking. Regardless if it comes from the starter relay or a tap on the ignition switch, that circuit is working. It isn't shown on my version of the diagram.

Let me know what you find up to this point, and give me an idea of how comfortable you are with electrical diagnosis and reading meters.
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Saturday, September 16th, 2023 AT 8:19 PM
Tiny
ALTHEA MAYBERRY
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I'm sorry, I guess I should have mentioned that I have a single ballast installed which was on the truck when I got it. Previous to my current truck, I had another 85 Dodge D150 and it was still factory. It too had a single ballast resistor.
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Sunday, September 17th, 2023 AT 5:36 AM
Tiny
CARADIODOC
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The story is the same. Just disregard the second resistor in my drawings.
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Sunday, September 17th, 2023 AT 6:16 PM
Tiny
ALTHEA MAYBERRY
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We used the test light as you said and tested the power going to the starter regulator at the connection for the ballast. There is power going to the ballast connection in the crank mode but none in the run mode. Nor is there power going to the ECU or the ignition coil.
I thought I might add that I have had to do some rewiring and my friend, and I believe that I may have forgotten to hook something up or I hooked something up backward. But what? I don't know.
The extensive work I have done required unhooking a bunch of things under the hood because I did the head gaskets and manifold gaskets as well as installing a new timing chain assembly. I don't know if adding this information helps, but it does give you a broader view of what I have done.
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Monday, September 18th, 2023 AT 11:00 AM
Tiny
CARADIODOC
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Wonderful. So we have 12 volts coming in on the pink wire for the resistor bypass circuit during cranking, but it's missing in the "run" mode for normal operation, (little red arrow). I pieced the two Chrysler diagrams together to make them easier to follow. The dead circuit is "J10 14RD. That's a 14-gauge red wire. Follow that back to the splice J10, (bigger red arrow). There's another diagram in between but it didn't reproduce well and at least for now, it isn't needed. The second diagram is for the ignition switch where circuit J10 originates. Actually, none of these reproduce very well. Get as far as you can, then I'll try to find something better. You can try copying them into a typing program like MS Word where you can make them bigger, if that will help.

In the first diagram, I followed it backward to J10. In the second one, it's easier to explain if we start at the blue arrow and follow it forward to J10. That's coming from a fuse link wire which is a good suspect. If you know where it is, tug gently on it. If it acts like a wire, it's good. If it's burned open, it will act like a rubber band. The circuit goes through a curved connector at the base of the steering column, (smaller red double arrow). Those terminals are another good place to find a badly burned or overheated connection. Check for 12 volts on both sides by back-probing those terminals alongside each wire.

Next, it goes to terminal "B1" on the ignition switch. That is another good place to find an overheated connection. Same with where it comes out on terminal "I". At this point, the ignition switch must be in the "run" position for 12 volts to be on the circuit. Next it goes to the connector again, (bigger red double arrow), and another good place to find burned terminals. After that connector, they show it feeding two fuses, 11 and 12. Look for those in the fuse box. They will have two tiny holes on top for test points. This is a dandy place to break the circuit in half. Let me know what you find on those fuses. If there's 12 volts, the defect is further down the circuit. If there's 0 volts, we have to look back toward the battery or fuse link wire.
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Monday, September 18th, 2023 AT 8:17 PM
Tiny
ALTHEA MAYBERRY
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Hello Caradiodoc. I thought I'd give you an update. We've had a bit of rain since we last conversed, and then over the weekend, my friend who's been assisting me had his 61st birthday on Saturday, and then on Sunday he went to a NASCAR race. However, I think we may have pinpointed the problem to either the wire that comes out of the bulkhead, inside the cab, to the ignition switch for the ignition feed, or it may be where the wires connect to the bulkhead. We had a difficult time taking out the part of the bulkhead that goes through the firewall. By the time we got it out, it was pretty hot outside, so we quit for the day. This morning I am going to check the connections in the bulkhead and try cleaning them. I'll let you know what I find out.
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Wednesday, September 27th, 2023 AT 6:53 AM
Tiny
ALTHEA MAYBERRY
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Hello again Caradiodoc. Here's a new update. I did an Oms test on the red wire on the cab side of the bulkhead and it's throwing an enormous number of 93.1 Oms. The blue wire is at 1.4 Oms. It's not supposed to be throwing that big of a number, right? If not, what's the best way to go about fixing it?
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Wednesday, September 27th, 2023 AT 8:16 AM
Tiny
CARADIODOC
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You are so correct. That's way too high. That red wire feeds a lot of stuff under the hood. To do a quick double-check, turn the ignition switch to "run", then look on the back of the alternator for the two smaller wires bolted to the two brushes. One of those will also be red. See what you have for voltage there. It should be full battery voltage. If you find it's real low, a test would be to use a long jumper wire between that red wire and the positive battery post. Multiple things will come to life.

The terminals in bulkhead connectors and that curved connector at the base of the steering column were known for burning up due to the high current flow through them. There's a couple of ways to address this. First, if you see the connector body is melted, or the terminals are black, there's no saving them. They develop a little resistance between the mating pair of terminals. That resistance causes heat when current flows through it. That heat causes more resistance, and keeps snow-balling until the terminals turn black.

One repair is to cut the burned terminals out along with the melted plastic around them. Install new terminals, then plug them in separately after the rest of the plug is reconnected. Any time you do that, the wires will be hardened from the heat for about four inches. Solder won't adhere to that, so you have to cut off that four inches, splice in new pieces of the same gauge, then use a pair of universal crimp-style terminals, but solder them too for the best connection. This was real common too on mid '90s ignition switches, and I've run into it on head light and dimmer switches. Heater fan switches can also develop these overheated terminals.

The second method of repair is to just cut out the terminals and the four inches of wire on each side, then slice in a connecting wire with no terminals. The bulkhead connector is only there to put the vehicle together on the assembly line. It isn't needed after that as it does not provide a convenient place to take readings or do other tests. Same with the steering column connector. You only need that one if you replace the entire column. It's a better repair to splice in a jumper wire around the connector, with no terminals.

Keep me updated on your progress.
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Thursday, September 28th, 2023 AT 10:43 PM
Tiny
ALTHEA MAYBERRY
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Thanks, Caradiodoc. I did check the connectors on the bulkhead on both sides and the ignition switch half-moon connector on both ends and, luckily, they're not burnt. Resistance testing on the terminals themselves checks out normal. I'll try your test method for the alternator wire that you mentioned.
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Friday, September 29th, 2023 AT 6:15 AM
Tiny
KEN L
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Please let us know what you find.
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Monday, October 2nd, 2023 AT 10:46 AM
Tiny
ALTHEA MAYBERRY
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Hello again. I did the suggested test on my alternator, and this is what happened: nothing. Nothing lit up. However, I left the battery connected for approximately 5 minutes, while I went next door to talk to my mechanic friend who's been helping me. After I returned to my truck, I discovered that the red wire on my alternator was hot to the touch. Also, my wire-piercing probe melted. What's the matter with this?
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Monday, October 2nd, 2023 AT 12:01 PM
Tiny
CARADIODOC
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That circuit draws a lot of current. Besides that field terminal on the alternator, the red wire feeds the voltage regulator, the ballast resistor for the ignition module, the electric choke heater, and possibly a few other things. When the engine is not running, meaning electrical system voltage is low, the voltage regulator is going to try to run the alternator wide open to get system voltage up to where it should be. Under that condition, field current through the alternator's brushes and the voltage regulator will be close to three amps. That's the equivalent of three brake light bulbs. I never measured current through the choke heater, but I would guess that could be another two or three amps. The ignition module turns on to allow current flow through the ignition coil, then pulses it off roughly 50 percent of the time when the engine is running. That's another couple of amps, but it turns off half the time, so the average is less. With the engine not running, that module is going to be turned on constantly, waiting for the timing signal to turn it off briefly. All those things added together, it's not unrealistic to find ten amps flowing through that circuit. That's the same draw as two low-beam head light bulbs.

Wire-piercing anything was never allowed in my classroom. If I found a pierced wire on one of my "bugged" cars, the offender was invited to replace the entire wire. WAY too many problems show up in the future from moisture getting in and corroding the wire. For our GM-owning friends, GM was using a lot of aluminum wire throughout the '80s. They had huge problems even without cutting into wires, especially at the fuse boxes. Those sat in front of the brake pedal where water and salt from shoes could get to the brass rivets inside the fuse boxes and cause corrosion. If someone did poke a hole in the wire's insulation, that section could turn to powder in as little as a couple of weeks. Instead, follow the wire to a connector terminal and back-probe it there to take a reading.

There's a couple of better ways to approach this. If you suspect something on that line could be shorted to ground, disconnect the negative battery cable, then use your ohm meter to measure between anyplace on that red wire, to a clean, rust-free point on the engine or body. If you find close to 0 ohms, unplug the voltage regulator, the ignition module, and the choke heater to see if the resistance goes up. With no power to the system, nothing will be turned on, so you should find a pretty high reading. I expect to find nothing shorted because you would have gotten a huge spark when you connected your test probe.

A better way to diagnose this, when you think something is drawing excessive current, is to use a light bulb in that jumper wire. I put together a dumbed-down set of drawings that I hope any competent do-it-yourselfer can follow to show how this is done. You won't have any trouble understanding the concept, but I have to explain a couple of changes. First, these are for powering up a circuit that is blowing its fuse. It's done by replacing the fuse with a bulb. I have another set of drawings for doing the same thing by bypassing the relay. Either one lets you work in the circuit with power applied. The bulb limits current to a safe value when the short is present.

The first change is you don't have to go to a fuse or relay. Just connect the bulb in series between the battery's positive post and the red wire. Second, the 3157 brake light bulb in my drawings won't pass enough current. You're likely to see little difference in brightness between having a short on that line vs. Normal operation. Instead, substitute a head light bulb for the brake light bulb. Brake light bulbs draw one amp. A 9004 or an older sealed beam bulb will pass close to five amps on the low beam, and six amps on the high beam.

What you will find with the head light bulb is if the circuit has no short, it will be on but much less than full brightness. If there is a short, or if you want to experiment and ground out the red terminal at the alternator, you'll see the bulb go to full brightness. No more than five amps will pass through the bulb, so the wiring is protected.

With a jumper wire that can handle the current, and no short on the red wire, the engine should run. When the bulb is added to that jumper wire, it may drop too much of the 12 volts, leaving too little to power the ignition module and coil. If that bulb's brightness indicates there's no short, remove it and run the jumper wire directly to the red wire. If the engine runs, it just proves everything under the hood is okay. We still have to find where the 12 volts isn't making it from the ignition switch to under the hood.

I have one more comment of value, but you're free to disregard this if it will confuse the issue unnecessarily. That has to do with replacement alternators. All generators require three things to work. They must have a wire, (coil of wire), a magnet, (we use an electromagnet because it's easy to adjust its strength), and most importantly, movement between them. That's why we spin the electromagnet with a belt and pulley. Electromagnets are always a wound-up wire with two ends. Those are what the two brushes are connected to so the "field" coil can rotate, and that's what the two smaller wires are bolted to on the back of your alternator. Either wire can go to either brush terminal.

That wasn't the case in the earlier versions. The "AC generator" was one of Chrysler's many innovations that other manufacturers copied. They even copyrighted the term, "alternator". In those early versions, from 1960 - 1969, field current passed through the voltage regulator first, then to the field coil in the alternator, then to ground. That meant one of the field brushes was mechanically bolted right to the unit's housing to ground it. There was only one small wire to connect.

Starting with the 1970 models and the introduction of the electronic voltage regulator, (another Chrysler innovation), field current flows to one alternator brush first, through the field coil, out the second brush and terminal, over to the voltage regulator, through it, then to ground. To say that a simpler way, neither field terminal on the alternator is grounded. Where you see those brushes bolted on, there's fiber insulating washers under the bolt heads.

The potential problem is due to the fact the newer design can be used on the older car models. One field brush has to be grounded, and that was accomplished by the rebuilder supplying an extra metal washer to replace one of the fiber washers. The other insulated terminal was still used with the one smaller wire. No other wire had to be attached to the brush with the steel washer as it was now grounded.

The problem is once that modification was made, simply switching the one washer, that alternator was going to show up on the shelf at a salvage yard sooner or later. With only a quick glance, that metal washer could be overlooked. If that alternator was installed on a newer vehicle, one of two things would happen. If the red 12-volt feed wire, (blue on most car models), was attached to the grounded brush, you'd have that dead short. If it was attached to the insulated brush, the grounded brush would be bypassing the voltage regulator, so the alternator would charge wide open. That leads to blown bulbs and a badly over-charged battery. I'm only mentioning this because with all the things you mentioned from the previous owner, there's the chance this problem could be involved here.
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Monday, October 2nd, 2023 AT 4:30 PM
Tiny
ALTHEA MAYBERRY
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Hello again. After unwrapping all the wiring in the engine compartment, I discovered that the insulation on the wires was cracked and breaking apart. The wires are very stiff as well. I've put too much time and money into this project to quit now, so I will be replacing all the wiring. I've already begun with the 14-gauge red wiring. This will take a while. I found these new kinds of splice protectors. They are clear heat shrink tubing with solder in the middle. They are called Solder Seal Wire Connectors. I hope they work as well as described in the videos I've seen. I've already used some of them and they seem like they will work just fine.
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Friday, October 6th, 2023 AT 7:52 AM
Tiny
CARADIODOC
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My friend found those too at a car show swap meet. They do indeed seem to work, but I do have some concerns. The way the strands of wire get poked into each other in those connectors is exactly the way I do it for my repairs, especially where I splice in new sections between the door hinges. My concern is wires with insulation that has been cracked for a few years will have let moisture in, and that leads to a brown coating of corrosion on copper wires. I make sure to scrub that clean until I see only bright, shiny copper, then I splice the two ends, solder them, then seal them with moisture-proof heat-shrink tubing. I'm sure a lot of people are going to stuff the wires together without shining them up first. Solder will not make a solid electrical connection through that coating of corrosion. I can see a lot of problems in the future due to intermittent connections.

The other thing I question is how that solder can melt at such a low temperature. Regular solder that I've used for decades in tv and car repair melts at around 500 degrees. You need a soldering iron to get the temperature of the parts that high. It is not proper to melt the solder with the soldering iron. Doing so burns away the flux leaving molten solder that will not flow correctly to adhere to the parts. Instead, proper procedure is to use the soldering iron to heat the parts, the wire strands in this case, then those parts must get hot enough to melt the solder that's touched to them. Molten solder will flow through the wire strands toward the heat source, so you touch the solder to the side opposite of the iron and let it flow to the iron.

Once that solder joint has cooled, the heat-shrink tubing is slid over it, then heated with a hot air gun, similar to a hair drier. The temperature those get to is more than enough to shrink the tubing and melt the hot-melt glue inside them, but not nearly hot enough to melt the solder and let the splice fall apart.

Now we have these connectors with solder that DOES melt with a hot-air gun. What's different about it and will it hold up as well, or develop problems in the future?

My last concern has to do with standard good soldering skills. Proper techniques start with forming a solid mechanical connection, THEN a good electrical connection. By that, I mean you don't just lay two wires next to each other, or touch a wire to a terminal, throw a little solder on them and expect it to hold. Normal vibration will cause those parts to crack apart over time. Instead, we crimp terminals to wires first, or twist the ends of wires around each other first, to form the mechanical connection, then solder them to form the electrical connection. I've seen similar splice connectors that have a metal barrel that must be crimped with a special pliers to form the mechanical connection, then the tube is heated to shrink it and form a seal, but there's no way to get solder in there for the good electrical connection. These new connectors should make the good electrical connection and seal out moisture, but there's no solid mechanical connection first.

While these do seem to work, time will tell how well they hold up. I have a 2014 Ram that was a crash rebuilder. I've been driving it since it had 4200 miles with a broken connector by the left front wheel. Someone at the yard I bought it from planted a bunch of non-moisture-proof butt connectors in place of that connector so they could drive the truck around the yard. I haven't replaced the connector yet, but when I do, I'm not ready to trust these splices. I'll be using my normal method, but one frustration has always been holding the two wires together while they're being heated and soldered. Recently I found a special pair of pliers made for just that purpose. It locks in place with the wire strands interconnected and holds them while you do the soldering. This connector could just be eliminated as it is only needed to put sections together on the assembly line, but I like the idea of having it there to provide legitimate test points. I've replaced a half dozen of these on other rebuilders at my friend's body shop. It seems to be the first thing to get damaged in a crash. In later years it was moved to a more protected location, and still later it was removed entirely from the wiring harness.

I haven't run into the type of wire problems you found. I'm wondering what caused the damage. It sounds like it's heat-related, like a section was too close to hot exhaust parts or some heat shield got removed during other services and didn't get reinstalled.

Keep me updated on your progress.
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Friday, October 6th, 2023 AT 5:49 PM
Tiny
ALTHEA MAYBERRY
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Hello again. Before I answer your last response to my last post, I first need to ask a question. I am providing a photo so you will understand what I am asking. I am working on the red 14 gauge wires that is under the dash which goes through the bulkhead. The red wires look like they are spliced with a pigtail. Two wires morphing into one. They are being held together by a thing that looks like a small barrel. Is that also a fusible link? Or is it just a very strong connector?

Now to answer your post. Truthfully, I also wondered the same thing about the Solder Seal Wire Connectors because I do know it takes a lot of heat to apply solder properly. Especially after I connected the first two wires together. I noticed that the solder didn't seem to be melted. My friend and I thought that it could cause a problem. Yes, I understand that the wires need to be heated first and then the solder applied to the hot wires. I didn't know that there is a special tool to help hold the wires as you're soldering them. What's the tool called so I can get one?

As far as twisting wires together. I do it the same way as shown in the photo with the red wires twisted together. This is how my automotive instructor taught me how to do it in the 89/90 school year. I had a 1972 AMC Matador and I switched out the 6-cylinder inline engine for a V8. The alternators were on opposite sides, so I had to add some wiring. This is also when I learned how to solder and seal it with shrink tubing. Although I did take automotive repair classes, there is still a lot I don't know. I'm more of a hands-on learner than a book learner.

The wires in the engine compartment mostly ran across the firewall, just under the hood. A couple of months ago, I thought I was done with that part of the wiring, so I wrapped it back up with insulated cloth tape. However, after being in contact with you, I decided to unwrap it again because of what you said about broken wire insulation. Although I already knew of the broken insulation, I didn't know about the pliability and the corrosion, so I checked for pliability and corrosion. The red 14-gauge wires are stiff all the way to the 5-way splice on both sides of the splice as well as corroded and brittle, which as to why I am replacing the red wires. However, I don't know what I am going to do about the 5-way splice. The whole thing needs to be replaced. There are other wires in the harness that are the same way.

I don't know how long this is going to take, but I plan to rewire everything as well as thin out and eliminate what is not necessary. Such as the wiring for the A/C unit. The A/C compressor and mounting bracket are missing, so I don't need the wiring for that. This part of my project is going to take some time.
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Saturday, October 7th, 2023 AT 12:19 PM
Tiny
CARADIODOC
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On your first photo, I've seen those too, but never really paid much attention to them. If that is one wire feeding two fuse link wires, the two will be of a smaller diameter for up to about six inches, then there will be another splice and the wire will go back to a larger diameter. That makes the smaller fuse link section the weak link in the chain. The insulation on fuse link wires is dull, and chances are it will be a different color. Their current ratings are denoted by the color of the insulation, and I don't think I've ever seen red. Orange, gray, white, and black are common. The wire is regular wire. It's only the insulation that is special. It is designed to not burn or melt. If the two wires are red and shiny, it's more likely they're just two different circuits. It's less expensive to use a splice rather than run both wires all the way back to their point of origin.

You purchase replacement fuse link wire from any auto parts store. You'll get a piece about 12" long which is more than enough to make two or three repairs. The length of the installed section is not important. All that is important is there is something in there that's smaller than the rest of the wire it protects. In fact, you can splice and solder the ends of the old fuse link together too to make the repair once the short is solved. As long as some of the original wire is still there, the circuit is still protected.

As a point of interest, you can harvest a whole handful of fuse link wires at any salvage yard from an older Dodge Shadow or Plymouth Acclaim, and their twins. Those front-wheel-drive vehicles have about a dozen of them in a bundle running around the left front strut tower under the hood. Typically you'll see mostly white and a couple of gray wires.

As long as I'm sharing all this wondrous information about fuse link wires, these are used in high-current circuits, and they act like slow-blow fuses because they take some time to burn open. Current flow through a motor goes way up when it is stalled or locked up, or runs slow due to tight bearings. That will cause the link to burn open eventually. A motor that's just starting up when power is first applied also draws high current for a couple of seconds until it gets up to speed. That's where a regular fuse could blow but there's no actual defect in the circuit. Fuse link wires tolerate that momentary high current.

There is one huge drawback with fuse link wires that isn't an issue once you understand what is happening. In one case in particular, a very experienced former coworker who didn't like me, came over with his tail between his legs and asked for my help years ago with a radiator fan problem on a K-car. The old fan motor had tight bearings, so he ordered a new one. Couple of days later he installed it but it wouldn't run. He used the scanner to cycle the fan's relay on and off and found 12 volts pulsing on and off on the motor's positive wire. Ground wire was okay. In his mind he had ground, 12 volts, and a motor that runs when he jumps 12 volts to it, yet it doesn't run in the car. All I told him at first was to recheck the 12 volts with a cheap, standard test light instead of his expensive voltmeter. He looked confused, but came back a few minutes later and said now he does not have 12 volts pulsing on and off, and he found the fuse link wire burned open. He was my buddy after that. There was nothing wrong with his diagnosis, except he didn't go far enough.

Digital voltmeters work by measuring electrical pressure, (voltage). To do that, it takes just barely a tiny tickle of current to do that. The drawback I started to describe about fuse link wires is when they burn open, the last step is for some arcing to take place between the two ends of the wires. That arcing leaves a carbon track behind on the inside of the insulation, similar to what we often found inside distributor caps. That little film of carbon can pass enough current for a voltmeter to see 12 volts at the end of the line. Think of having 50 psi of water pressure at a faucet and at the end of the garden hose. That carbon track would be like standing on the hose and blocking it by 99 percent. You'll still have 50 psi at the nozzle, ... Until you open the nozzle and try to get some water flow, (current). Barely a dribble of water will get through, and now, with the nozzle open, you don't have 50 psi there anymore.

What would have made the K-car problem faster to find was if he had taken the voltage reading with the connector plugged in. By unplugging it, that was like having the hose nozzle closed off. Full pressure will still be at the nozzle as long as you don't have the hose 100 precent blocked with your foot. That 50 psi is a false reading. It isn't there when you want the system to do some work, in this case, spray water. The 12 volts he had at the motor's connector was there until he connected it to the motor and tried to get enough current to do some work, then it was gone.

The old-style, common test light with an incandescent bulb inside requires current flow through it to do its thing. Not enough current can get through the carbon track to make the test light turn on, so it gives the more accurate result.

This applies to any high-current circuit like heater fans, head lights, charging systems, wipers, and things like that. Besides just checking to see if you have the required 12 volts, you must also see if the circuit can pass the needed current. There's two ways to make it want to draw the required current. One is to simply plug in the item it runs. That was the radiator fan motor in my sad story. That's the time to take the voltage reading, but in some cases that can be hard to do. Being plugged in to get valid readings also applies to sensor circuits. With those, there's usually rubber weather seals around each wire where they go into the connector body. That's a perfect place to poke the meter's test probe. Radiator fan plugs are designed to seal out water when they're connected, but if you're careful, you can usually pull them apart just enough that they stay connected, but enough of the terminal is exposed to allow you to take a reading.

So keeping the circuit connected is one way to see if it can pass enough current. The second way is to use a test light instead of a voltmeter. Test lights don't draw nearly as much current as do motor's, but they at least draw some. Voltmeters draw so little, for all practical purposes, we say they draw no current.

In your second dandy photo, you've created the mechanical connection I described. The solder will provide the electrical connection next. When I do door wiring, I don't even twist the strands together. I prefer to just slide the strands from both wires into, or through each other, twist them just enough so they hold together long enough to throw some solder on them, then I slide the heat-shrink tubing over and warm it. I'm less concerned with the solid mechanical connection because when I do these on older Caravans, it takes 11" of wire, but I pull the old wires out of the "A" pillar and out of the front of the door, then splice in 22" of each new wire. There can be up to 22 wires if the van has door speakers, courtesy lights, power mirrors, and things like that. When I'm done, I push the splices inside the front of the door where they aren't going to flex. Half of what remains gets stuffed inside the "A" pillar, but you gotta watch that it doesn't coil up on the parking brake assembly. That puts those splices inside too where they won't be flexing. If that repair ever needs to be done again, you just pull the extra out of the "A" pillar and you're half done. Only have to cut and splice on the door end of each wire.

I also got a chuckle out of your comment, " I'm more of a hands-on learner than a book learner.". In my three miserable years in college, one of the very few things of value I learned was that different people learn best in different ways. I knew that already, but needed to hear it from someone else to solidify my thought. Years later I used that comment in my classroom when explaining why electrical theory and suspension and alignment theory are so difficult to learn. It's because people in Automotive classes, carpentry programs, and other hands-on programs typically learn best by taking things apart, manipulating those parts, and seeing how they interact. People good at Electronics learn best by hearing descriptions and visualizing theoretical concepts. A confused Automotive student, simply made aware of why electrical theory is so hard to learn, finds it a lot easier after knowing why, especially when I can compare anything electrical to water flow, which is something we've all seen and played with. We had to have our book learnin' too, but if you did that the night before, you had questions the next day in class, and that formed the basis of our "class discussions" before we went out to the shop for the day.

I have to add one more comment of value. In nine years of teaching Automotive, three of my top students were girls, and the guys had a lot of respect for them. I don't know if they just tried harder than the guys who grew up in the field, but one in particular would run you over with enthusiasm when she was given a job to work on. We had a lot of fun in our shop.

As before, keep me updated on your progress, and bring on any other questions.
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Saturday, October 7th, 2023 AT 6:00 PM
Tiny
ALTHEA MAYBERRY
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Hello again. I guess I should have told you where the red pigtailed wires go in the photo. The single wire goes into the fuse box and the other two, one comes from the bulkhead connector and the other goes into the half-moon connector for the ignition switch.

When I began my automotive class there was one other girl besides me, but she didn't stay long. I guess she decided she didn't like it and dropped the class.

Anyway, I was brought up around cars. My dad fixed cars as a side job in my grandma's backyard and I was always poking my nose in his business. By the time I was 6, I knew more about cars than any other 6-year-old. After he was discharged from the Navy, he went into stock car racing. He built his own cars and raced them for several years. Then about 1966, he learned my mom was pregnant with me, and then he got into a wreck while racing one night and landed in the hospital for several days. After that, he decided to quit racing, went into paint contracting, and did backyard mechanics.

Also, every boyfriend I ever had, except for two, were mechanics, and I was married for 30 years to a mechanic. So, I do have a pretty extensive background in automotive. I prefer old vehicles as opposed to newer ones. I don't like all the junk covering the engine and it's harder to do what should be a simple tune-up. I don't know everything and this is my first time tackling a major wiring issue.
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Sunday, October 8th, 2023 AT 10:54 AM
Tiny
CARADIODOC
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First weekend after July 4th for the last 20 years I sit in the swap meet of the nation's second largest old car show at Iola, WI and sell and repair car radios, mostly Chrysler stuff. Make a lot of new friends every year. In conversations, about one out of three people can't stand all the unnecessary use of technology, meaning computers to do things that never needed computers before. There's a huge market up here for those who drag older rust-free cars up from down south. I still have my first new car, an '80 Plymouth Volare, with 45,000 miles. What a pleasure to drive. Also just dug out my only other new car, a '93 Dynasty with just under 5,000 miles. Doubled the miles I put on last year. This year I drove it two miles. So comfortable and quiet.

Anyway, I agree with your assessment. There's no arguing cars today are cleaner, and no one wants to go back to the old days in that respect, but if my carbureted Volare can consistently get 28.3 mpg with a 4,400 pound car with chromed steel bumpers, why can't a little plastic car that weighs half of that get 80 mpg with all the current technology?

Now I'm disgruntled. Will need to go shopping in Home Depot. That always helps.

As before, please keep me updated on your progress with the wiring problem.
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Sunday, October 8th, 2023 AT 2:46 PM
Tiny
ALTHEA MAYBERRY
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Hello Caradiodoc, I just thought I'd give you an update on my truck. I'm just taking my time going through the wiring. However, I have taken a big break from this project and haven't worked on it since the middle of October.

Thea
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Monday, December 11th, 2023 AT 1:35 PM

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