Alternator not charging

Tiny
BSPEEDO77
  • 2004 DODGE RAM

Electrical problem V8 Four Wheel Drive Automatic 58000 miles

The alternator on my 04 dodge ram does not charge the battery. I have replaced to alternator and the battery. I have also changed the fusible link that is between the alternator and battery.I have checked the cable that goes from the B+ terminal on the alt. To the battery with a circuit tester and it is good. I have also checked the 3 ground wires off the negative post of the battery and can't find anythng wrong with them. Please help.

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Monday, May 24th, 2010 AT 8:28 AM

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Tiny
CARADIODOC
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Hi bspeedo77. Welcome to the forum.

The alternator is regulated by the ECM Here is a wiring diagram and a guide so you can do some tests to see if it is a wiring issue before replacing the ECM unit.

https://www.2carpros.com/articles/how-to-check-wiring

and

https://www.2carpros.com/articles/how-to-check-a-car-alternator

You did step one already, now measure the voltages on the two small wires on the back of the alternator while the engine is running. One must have full battery voltage, the other one should have less than battery voltage, but not 0 volts. Holler back with your findings.

Alternator wiring diagram (below)

caradiodoc

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Monday, May 24th, 2010 AT 12:32 PM
Tiny
BSPEEDO77
  • MEMBER

I tested both wires and both were at almost 0. I found the wires and splice on a 4.7L Ram but I have a 5.7L Hemi and I'm not really sure where the splice is.

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Tuesday, May 25th, 2010 AT 11:31 AM
Tiny
CARADIODOC
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Unfortunately all three of my laptops puked that got me access to Chrysler's web site so I can't see the wiring information for a 2004. My newest paper service manual is for a 2000 which has different engines. Still, most of wiring should be similar. I may have told you the wrong wire color. Dark green with and orange strip is common for most cars, but for the 2000 truck, they used a dark blue wire to feed the field winding. That originates from connector 3, pin 25 of the Powertrain Control Module.

From previous experience building a "bug" into a '97 Dakota for my students to troubleshoot, I learned that the 12 volts coming into the PCM goes directly to the pin going to the alternator. The only way to have a problem inside the PCM is if the copper circuit burns open due to improper testing techniques, (shorting that circuit to ground). Therefore, if you are missing 12 volts at the blue wire at the alternator, the chances of it being a PCM problem is very low. However, the 12 volts coming into the PCM feeds other circuits too so there should be other symptoms besides the no-charge.

My new laptop just showed up this morning. I'm going to set it up and see if it will allow me to access the Chrysler web site. If it does, I'll post another reply with the correct wire color and pin number.

Caradiodoc

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Wednesday, May 26th, 2010 AT 2:03 PM
Tiny
CARADIODOC
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Boy, this is really depressing. I had this circuit memorized. It has not changed in decades, ... Until now! Forget everything I told you previously. One of the small wires on the alternator is grounded. It's a brown wire with black stripe. There must be some voltage on the other wire, the brown with gray stripe. That voltage comes from connector # 2, pin 19 of the Powertrain Control Module. The 12 volts coming into the module is on connector # 1, pin 29. That's a red wire. All of them are 20 gauge which is very small. The feed voltage comes from 20 amp fuse number 23 in the Integrated Power Module which I think is by the left head light area.

Check that fuse. In the past, that 12 volts was turned on by the Automatic Shutdown (ASD) relay which also sent power to the coil(s) and injectors. It appears on your truck the current to the alternator field is turned off by the Powertrain Control Module; another trouble-prone computerized switching circuit. If it appears the PCM is not turning the alternator's field current on, I can walk you through the steps to installing a 1972 - 89 external voltage regulator that will run the system just fine although it's possible the Check Engine light will turn on. I'm going to be doing that to my New Holland Skid steer this afternoon. The alternative is to replace the PCM. Lets hope it's just a popped fuse.

Caradiodoc

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Wednesday, May 26th, 2010 AT 2:55 PM
Tiny
BSPEEDO77
  • MEMBER

I had already checked fuse #23 and it was good. I had figured that I was going to have to change the PCM also. If you could tell me how to hook up a external regulator that would be much appreciated. Also where could I get the external regulator?

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Thursday, May 27th, 2010 AT 7:47 AM
Tiny
CARADIODOC
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You'll find a bazillion of them in the salvage yards. All domestic Chrysler products used them from 1970 through at least the early '80s. I think they were used through the '89 model Fifth Avenue rear wheel drive. You can also buy a new regulator for around 15 bucks. If you have a farm and home type hardware store, they will usually have them too.

They were mounted to the passenger side of the firewall and have a triangular three-pin connector but there were only two wires in it. The wire in the center is blue. The one on the side is green.

My personal preference for your truck would be to disconnect the plug or unbolt the terminal block from the back of your alternator and wrap it up so it can be easily put back to stock in the future if desired. Find a similar connector in the salvage yard to hook the new wires to it. Of course, grab the connector for the regulator too. It is held on with a spring-metal band that you have to squeeze on the sides to release the locking tabs.

Ok, here's where it gets complicated. You have two small wires on the back of the alternator that were bolted on or plugged in, (depending on the year). You have two terminals on the regulator. Connect the two pairs together. For simplicity, use green and blue wires to extend them from the regulator to the alternator. Either wire can be connected to either terminal on the alternator as they are just going to the two ends of a coil of wire. Polarity doesn't matter. (I hope you understand I don't mean tie all four points together). Connect the blue wire from the regulator to one terminal of the alternator. Connect the green wire from the regulator to the other terminal on the alternator. There, the hard part is done!

Only two more connections are needed. The first is simply to bolt the regulator to a clean, paint-free surface on the body. That is the ground connection. Don't go scratching a lot of paint off. The threads of the bolt should cut into bare metal just fine. The last connection is to splice into the blue wire and tie it to a circuit that turns on when the ignition switch is turned to "run". For many years, Chrysler used dark blue wires under the hood for any circuit that turned on with the ignition switch. I don't know if they still do that. You might look at the "park" wire on the wiper motor. I can help figure out something to tap into if you can't find anything.

That's it. When the ignition switch is turned on, a small current, maximum of about three amps, runs from the blue wire, to the alternator, through the field coil, out the green wire, to the regulator, through its control circuitry to ground. The current through the field coil sets up a magnetic field. (Hence, the name "field" coil). When current flows through a wire, it sets up a magnetic field. When a wire is passed through a magnetic field, it induces a voltage which causes a current to want to flow. The secret to generating a voltage mechanically is you must have three things: a magnet, a wire, (a wire wound up into a coil is much more effective), and most importantly, movement between the two of them. The movement is why the field winding must be spinning. That's why it runs off the belt. The magnet is the field coil's electromagnetic field.

That blue wire serves two purposes for the regulator. It provides the power to run the circuitry in the unit itself, and it is where the regulator senses system voltage. The goal is to maintain alternator output between 13.75 and 14.75 volts regardless of how much current it is producing. Think of the regulator as a variable resistor between the green wire and ground. As the regulator senses a drop in voltage on the blue wire, it becomes a lower resistance for the green wire so more field current can flow. The increased flow causes a larger magnetic field to be produced in the field winding which results in increased output voltage which appears on the blue wire.

As with the regulator built into the Engine Computer, this external regulator has temperature compensation built in. That means it will raise the target system voltage a little bit in colder weather. Recharging the battery is a chemical process, and that process is not as efficient in colder weather. That's why charging voltage is increased slightly. It is decreased in hot weather to reduce the chances of boiling the water out of the battery.

Once the system is up and running, you might see the Check Engine light is turned on. The Engine Computer monitors that small field current to verify it is working properly. When the current doesn't flow through its internal circuitry, it will set a diagnostic fault code, "Field circuit not switching properly" in memory. Anything that can have an adverse effect on tail pipe emissions is supposed to turn the light on. Low system voltage affects injectors, ignition coils, and the fuel pump. If you find this to be the case, you can try connecting a resistor between the two wires you removed from the back of the alternator. That should mimic the resistance of the field winding and make the computer think it's doing something of value. A six to ten ohm resistor should work. Without doing the math, about a five watt resistor should work fine.

Caradiodoc

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Thursday, May 27th, 2010 AT 4:51 PM
Tiny
BSPEEDO77
  • MEMBER

I went to the auto store and bought a brand new regulator and wired it up exactly how your instructions said and it solved the problem. Thanks again 2Carpros!

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Wednesday, June 2nd, 2010 AT 7:26 AM
Tiny
CARADIODOC
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Please use 2CarPros anytime, we are here to help. Please tell a friend.

Cheers

caradiodoc

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Wednesday, June 2nd, 2010 AT 10:51 AM
Tiny
RBUSTER
  • 2004 DODGE RAM
  • 5.4L
  • V8
  • 4WD
  • AUTOMATIC
  • 150,000 MILES

Identical issue as on thread - installed a Chrysler voltage regulator - now the alternator overcharges. Battery at rest reading 12.35V easily starts the vehicle and the alternator delivers 15.00V. Slowly settles down to 14.6V at idle. 2K rpm always produces 15.00V. Tried a voltage divider (10ohm 24watt resistor) on the field lines but evidently the regulator circuit compensates to no avail.
A/C on, headlamps on - alternator holds at 13.45V at idle. 2K rpm - 15.00V!
Is there a way to throttle the field lines down? PWM?(I might as well try to design the entire voltage regulator)

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Friday, November 10th, 2017 AT 3:30 PM (Merged)
Tiny
JACOBANDNICKOLAS
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You have me a bit confused. The voltage regulator on this vehicle isn't a separate component, but rather a circuit located within the PCM and isn't something that is serviceable. If it is bad, the PCM needs replaced. Here is how it works. The electronic voltage regulator (EVR) monitors line voltage (B+) and battery temp. If the voltage is identified as being.5 volts or lower than the target voltage, the PCM grounds the field winding until it reaches.5v above target. A circuit in the PCM cycles the ground side of the alt and can do it 100% of the time.

As far as the alternator, although they look the same, different ones which produced different output ratings were used on these vehicles. Make sure, if you changed it, the one you got is the

Based on this, either the wrong alt has been installed or the PCM is bad.

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Friday, November 10th, 2017 AT 3:30 PM (Merged)
Tiny
RBUSTER
  • MEMBER

Please consider

http://www.2carpros.com/questions/dodge-ram-2004-dodge-ram-alternator-not-charging

Perhaps this will inform you as to what is happening. I completely understand how the computer is designed to control the voltage regulation. This is an attempt at a $50 fix as apposed to a $700 computer fix.

I am only asking this question here because of the fix presented in the forum.

Thank you

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Friday, November 10th, 2017 AT 3:30 PM (Merged)
Tiny
JACOBANDNICKOLAS
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I read the entire link. Although everything that was discussed should work in theory, there was never a conclusion that worked. I understand what they were trying to do, but I don't recommend it.

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Friday, November 10th, 2017 AT 3:30 PM (Merged)
Tiny
RBUSTER
  • MEMBER

Would it then be appropriate to ask for my money back?

It seems you should truncate this thread AND the one where I got the information to start this in the first place.

RBuster

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Friday, November 10th, 2017 AT 3:30 PM (Merged)
Tiny
JACOBANDNICKOLAS
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Yes, sir. If you go back to the homepage and log in, you can request a refund. I'm sorry about the confusion. As a normal policy, we only recommend OEM type repairs, so I'm not sure what to say about the one you found. As I mentioned, in theory it should work, but the way the newer vehicles are designed, it isn't recommended.

Again, sorry for the confusion.

Joe

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Friday, November 10th, 2017 AT 3:31 PM (Merged)
Tiny
BWOLFY699
  • 2004 DODGE RAM
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 211,000 MILES

The check gages light is on the battery gauge son the low side not charging replaced the alt still with the same problem

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Friday, November 10th, 2017 AT 3:31 PM (Merged)
Tiny
CARADIODOC
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Need four voltage measurements with the engine running. Measure battery voltage, the voltage from the alternator's output terminal to ground, and the two voltages on the two small terminals on the back of the alternator to ground. Measure at least to the tenth of a volt.

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Friday, November 10th, 2017 AT 3:31 PM (Merged)
Tiny
BULLDADDY
  • 2005 DODGE RAM
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 130,000 MILES

I need to know the color code for my 2005 dodge 1500 4x4 with 5.7 hemi. I am not charging. Replaced battery, alternator, computer so it has to be in the wires. We did a motor swap so I may have damaged my wires. PLEASE tell me the colors of the 2 field wires so I can identify and track them. Thanks

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Friday, November 10th, 2017 AT 3:31 PM (Merged)
Tiny
JACOBANDNICKOLAS
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First, check the integrated power module (fuse 23 / 15 amp) located at the left front fender. As far as the wiring from the alt, the fusible link is a brown/ red wire at the left rear of the engine compartment. The brown / grey wire is the gen field wire. The brown/black or brown/dark green goes to ground from what I see on the schematic. I suspect that either you have a blown fuse (#23) in the power module or the fusible link (brown / red wire) is blown.

Check that and let me know what you find.

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Friday, November 10th, 2017 AT 3:31 PM (Merged)
Tiny
RAM5
  • 2005 DODGE RAM
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 90,000 MILES

While driving home the check gauges light came on and I noticed the voltmeter went to "zero". Made it home, shut down and restarted. Gauge dropped to zero and light came on. Next day started truck and gauge showed charging with no warning light on. I checked voltage at battery (running) which was 14. 4. Shut down truck and checked across battery posts and got 12.7V. Went on to clean terminals/posts. Restarted and left running till the truck temp had heated to normal and again found alt was charging at 14+ volts. The following day took a trip to town with no problems however after shutting off truck and restarting to return home the check gauges light came back on and the voltmeter went to zero. Got home and check voltage at the battery (running) at 11.8V. I'm not sure if this is an alternator problem or not. Thank you for any help you can give.

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Friday, November 10th, 2017 AT 3:31 PM (Merged)
Tiny
HMAC300
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Check two items in pic if not those then have it scanned for codes it may be a tpim module problem.

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Friday, November 10th, 2017 AT 3:31 PM (Merged)

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