Mechanics

PLYMOUTH VOYAGER SENSOR PROBLEM

1992 Plymouth Voyager

I have 92 ply voyager turns over fine. No spark at coil. Don't have momentary 12v or 12v at start.
Avatar
Joey fitzgerald
October 27, 2012.




Do you mean no 12 volts at the ignition coil or injectors during cranking or for the first one second after turning on the ignition switch? If that is correct, swap the automatic shutdown (ASD) relay with another relay like it such as the AC compressor relay, then see if you get voltage on that circuit. If not, remove the relay and check for voltage on terminal 30 or 87. Sorry, I can't remember which one but one of them must have 12 volts all the time. If neither has it, a fuse is blown. If you do find it, feel if it is clicking when a helper turns on the ignition switch.


Caradiodoc
Oct 27, 2012.
I have tried recently to get an answer, I tried go back to an older question that was asked a couple of days ago. And I don't know if I should repost the whole thing or tryy to get an answer modified?


Tiny
Joey fitzgerald
Oct 28, 2012.
I had already swapped the asd relay and no luck but did not check for volts.I'll give it a try and let you guys know.I also checked the fuses, @fusible links. They all checked out ok.I was curious once the ecm gets all it's info, does it then and allow the asd to operate?I guess what I'm asking what power source feeds the asd, and ecm? What pin #on the ecm receives 12v? Or how much volts should present? And on more than one pin, thanks guys


Tiny
Joey fitzgerald
Oct 28, 2012.
On the asd relay, #30 has 12v, #86 has 12v/w key in run poss, #87 out To inj.@Coil.#85 should be grnd? Right? Using a conuity tester I don't have any. If I use a jumper to neg batt the asd works. How and where does #85 get it's grnd?
AD


Tiny
Joey fitzgerald
Oct 28, 2012.
I think I found it, pin #51 on the ecm. So I guess that there might be a problem with the ecm.


Tiny
Joey fitzgerald
Oct 28, 2012.
The web site changed last week to a new format and the site host is having a huge problem with sending out automated e-mails letting you and me know when a reply is posted. What I've been doing is right-clicking then opening each new question I read in a new tab, then I leave those tabs open so I can refresh them later to see if a reply was posted. Unfortunately I have well over 100 tabs open and it has slowed my really old computer to a crawl. If it went any slower it would be going backward! It is common to take 5 - 10 minutes to switch to a new page.

Don't start a new question as that will just make it worse. I started getting a few automated e-mails this afternoon. I noticed both of yours came through. On the site they are listed as you replied last night, but I just got the message at 1: 12 p.M. Today. Hopefully this will be fixed soon, then I may get flooded with hundreds of replies to answer. Sleep is over-rated anyhow.

As for your ASD relay, the 12 volts on terminal 30 is correct. That is the feed for the switched current to the injectors, coil pack, fuel pump, alternator field, and oxygen sensor heater. The 12 volts from the ignition switch to terminal 86 is also correct. That feeds the coil inside the relay. Terminal 87 does indeed need to be grounded but that is done by the Engine Computer. You can't measure that circuit for continuity. All you can do is watch its operation for that first one-second blip when you turn on the ignition switch. The easiest way to do that is to monitor the voltage we've been talking about from relay terminal 87 which goes to the injector, coil, etc. The second way is to feel if the relay clicks on, then clicks off one second later when a helper turns the ignition switch on. The third way, which is more time-consuming, is to place the probe of your test light on terminal 85 while the relay is installed, AND since you're testing for a ground, you have to move the test light's ground clip to the battery positive post. This way the test light will light up at the same time the relay is energized.

If any of those methods proves the relay is turning on for one second, that proves the circuitry is good and the computer has control of the relay. If the switched 12 volts shows up on 87 it should also be showing up at the coil and injectors. If it's at 87 but nowhere else, there has to be a break in that wire or a corroded splice.

Once you verify the 12 volts is showing up at the coil and injectors for one second, the next thing is it has to reappear during engine rotation, (cranking or running). If it does not, the computer isn't grounding the ASD relay terminal 85 because it doesn't know the engine is rotating. That is because a signal is missing from the cam or crank sensor or both. A scanner that displays live data will show both of them as "no" or "present" during cranking so you know which one to diagnose. If one signal is missing, suspect the sensor, its air gap, or a break in its signal wire. If both signals are missing, suspect a break in the 5, 8, or 10 volt wire that feeds both of them, a break in their common ground return wire, or the feed wire is shorted to ground by a pinched wire or shorted sensor. That feed voltage should be present all the time the ignition switch is on. If you don't find it at either sensor, unplug them and measure on the plugs after turning the ignition switch off and back on. If the wire or either sensor grounded out that feed line, the computer shuts that power supply down to protect it. Once the short is removed, you have to cycle the ignition switch off and back on to reset it. Missing the supply voltage to the sensors is not very common so we'll address that later if it becomes necessary.

Just for information purposes, you need 12 volts from the ignition switch to relay terminal 86 AND the ground on 85 to energize the coil inside the ASD relay. That is a double safety circuit and is extremely reliable and effective. In a crash that ruptures a fuel line, the engine can't run without fuel pressure so it stalls. That means no pulses from those two sensors so the computer turns the ASD relay off. That removes the 12 volts going to the fuel pump, or, on some models it also turns off a separate fuel pump relay along with the ASD relay. Either way the pump stops dumping raw fuel onto the ground where it would be a fire hazard. That wire between the computer and terminal 85 is only a few inches long but if it somehow got pinched or someone tried to modify it, the relay would still get turned off by turning off the ignition switch.

Unfortunately there is no easy way to know if the pulses are being received by the computer except with a scanner.

If you do find steady voltage at the coil and injectors during cranking, that indicates you have a less-common problem with one of the three individual circuits, the ignition coil, injector circuit, or the fuel pump. Of the three a dead fuel pump is the most likely suspect. You won't hear it hum for that one second after turning on the ignition switch. The coil pack would be next. You would have no spark but you would have good fuel pressure and you'd smell the raw fuel. If all the injectors were dead, suspect a break in the common wire feeding them from the ASD relay. Failure of one driver circuit in the computer is rare, and a total failure of all four, six, eight, or ten is unheard of. More commonly that would be caused by a blown fuse feeding the computer.


Caradiodoc
Oct 29, 2012.
Hi, and thanks for the info.I'm going to try to find the problem as you have suggested. Sorry about the repeets, and sorry to here about the computer problems, and missed sleep too.I have only a couple of other questions, 1 what fuse #feeds the computer.2 and which #s fuses feeds the cruise control, radio, overhead console? Thanks again for all your detailed help.I'm really glad your Web site is here, if I had either the techno or the resources to help I surly would. Once again thanks and I'll try not to bug you so much. Joey


Tiny
Joey fitzgerald
Oct 31, 2012.
There are multiple 12 volt feeds for every computer. Pin 9 is the 12 volts from the ignition switch "run" position. That circuit taps off and goes to fuse 14, a 2 amp, for the cruise control. That all comes off the ignition switch which is fed through an orange fuse link wire by the left strut tower. Pin 3 has 12 volts all the time. That circuit is tied in with the feed for the ASD relay, (16 gauge red / white wire). If that's missing, there's a 22 gauge white fuse link wire by the left strut tower. The other side of the ASD relay feeds the injectors and coil(s), and it goes to pin 57. That tells the computer it was successful in turning that relay on. Looks like those terminals are the same for all three engines.

Fuse 3, a 20 amp, feeds the power mirrors and radio memory circuit. That should be live all the time. If that fuse blows, suspect frayed wires between the driver's door hinges. Fuse 6, a 10 amp, is the switched 12 volts for the radio.

For the overhead unit it would be easier if you tell me what's not working. There's so many circuits feeding it for all the different lamps and rear vent windows that it's hard to follow. I see a 30 amp circuit breaker in cavity 25 but it just shows it going to a connector but it doesn't say for what.


Caradiodoc
Nov 1, 2012.
Hi guys had to take a day off. On the overhead console question it doesn't have fuel economy info, or compass info
The lights work but that is it.I went to the junk yard and
pulled one off another van I also pulled the two sensors that are in front of the radiator. But I'm not sure what's what.I installed the new console and a body control module, to no avail. So I thought it might be fuse related. But also not sure which sensor too install or if that's it. Also the two rear window open/closers work. The answers give me a direction to head in now on getting it running. Also unrelated to the van I've a question on a 2003 dodge ram 1500 v6 3.7ltr? The Speedo does not start working untill you reach 35, 40mph. How do I fix that? Also the brake@abs lights are on. The man said he installed new power booster, master cyl, and pads. How do I reset the system, if that's what it is? Also its unknown if, and when the Trans filter was changed 118456 mi. It should be of the ordinary. Changed shouldn't it? It not slipping or doing anything out of the ordinary. Once again thanks and I'll get that donation off in the next day or so. Joey


Tiny
Joey fitzgerald
Nov 3, 2012.
If the display is dead, that would mean a 12 volt feed or a ground is missing, but I can't find anything that would cause that if the lights are working. The only switched circuit is the tan wire but that has to be okay because it's the feed for the power vent windows.

You can also look at the two data buss wires. Those are the violet / brown and white / black next to each other in the connector. Those aren't needed for the lights and vent window motors but they might be what tells the display to turn on. The data buss signals come from the Body Computer.

If you have dashes in the display, the unit is working but that indicates a problem with the sensor. That should only affect the outside thermometer though. If the sensor is unplugged, the display should say "OC" for "open circuit".

For the speedometer, look at the speed sensor in the tail housing of the transmission. Look for stretched terminals in the connector although that will usually cause intermittent operation at any speed, not at a specific speed all the time like you indicated. Look at the plastic gear on the end of the sensor, (if that's the design they're still using), to be sure no teeth are worn down. A more likely cause would be the sensor itself has a partially-shorted coil of wire inside and must be replaced. Signals generated this way are a result of the strength of a magnetic field, the size of the coil of wire the voltage is induced into, and the speed of movement between those two. If the coil of wire becomes smaller, as in when it's partially-shorted, you'll need more speed to overcome the weaker signal that is induced into it.

The red brake warning light is due to low brake fluid level in the reservoir, the parking brake pedal isn't fully released, or there was unequal pressures in the two hydraulic circuits. First pull up on the parking brake pedal. If the light goes out the cable is stretched, misadjusted, or more commonly a cable by either rear wheel is sticking partially-applied. The switch on the parking brake pedal could be damaged too. Don't waste your time trying to bend them straight. Find a good used one in the salvage yard.

Unplug the level sensor on the side of the master cylinder reservoir. If the light goes out and the fluid level is okay, the float has sunk or the switch is shorted. If the level is low there is either a leak that must be addressed, the front pads are worn, but you said they're new, or the fellow didn't fill the reservoir after bleeding the system.

Unplug the wire from the combination valve on the frame, under the master cylinder. If the light goes out, the valve has tripped from unequal pressures. That can happen during improper bleeding procedures or when a leak was in one of the systems. That valve is spring-loaded but it often gets stuck. Once the condition that caused the valve to trip is fixed, it is sometimes necessary to jar it loose with a few hard, quick jabs on the brake pedal.

Don't worry about the yellow ABS warning light yet until the red one is solved. It will be on because the ABS Computer can't guarantee proper operation when there's some other problem with the base brake system pressures. Once the red one is off, you'll have to turn the ignition switch off and back on to reset the yellow one. If the yellow one stays on by itself after the red one is off, a problem has been detected and reading the stored diagnostic fault code will get you into the circuit or system that needs further diagnosis.

The transmission fluid is typically supposed to be changed every 36,000 miles. Mine on my '88 Grand Caravan has been changed once in 237,000 miles, at around 90,000 miles, and I use it to regularly drag around a tandem axle enclosed trailer that's bigger than the van. That is no longer neglect. That's abuse, and I don't recommend that to anyone.


Caradiodoc
Nov 3, 2012.

AD