2nd Gen Non-Engine/Transmission Code 41 on '94 Ram 2500

[Twisted Shifter]

Brief history leading up to the hard code.

I was at the track and had the IC pip blow off the top turbo. Went to the pits shut it down. Started it back up to load it on the trailer and the Check Engine light came on. Cycled the key and pulled several codes but the only hard code was a 41 (An open or shorted condition detected in the alternator field control circuit ) I assumed that the alternator had died and I had it checked. It was only putting out 3 1/2 volts. I bought a new alternator and installed it. I still have the same issue with the light being on and now voltage showing on the gauge in the dash. I thought I might have a bad alternator so I took it back off and had it checked. It tested good. I have looked all over and can not find any wires that appear broken or loose. I have seen guys talking about putting an old school regulator on and bypassing the PCM. Is this my issue? Did the voltage control go screwy in the PCM? Will it not work until the code is cleared?

Thoughts, ideas, what do I need to check. I can wrench on anything but wires scare me

 

[Twisted Shifter]

anyone? I bought a regulator, just want to make sure before I cut wires

 

[WilsonF]

It could be your problem, but you don't have to cut any wires. I just taped over the unused connectors on the harness to test it.

Truck no charge-y! - Page 2 - Dodge Diesel - Diesel Truck Resource Forums

Try this post, it has good instructions

Floyd

 

[Twisted Shifter]

It could be your problem, but you don't have to cut any wires. I just taped over the unused connectors on the harness to test it.



Truck no charge-y! - Page 2 - Dodge Diesel - Diesel Truck Resource Forums



Try this post, it has good instructions



Floyd

Thank you ... . I read it over and I have the external regulator, but that's not going to clear the code on the dash. I have done a bunch of reading and wanted to explore all options before I do that.



From what I am reading on my wire diagram ... . Pin 20 and 57 are the pins on the PCM. I pulled the block from the firewall to check continuity from the block to the Alt. I have continuity from pin 57 to one side of the alt field wire but nothing from 20 on either field pin. I tried this both with the key on and off. Does this mean I have a broken wire?

 

[Missouri Mule]

The wire going to the battery temp sensor gets corroded some times I would check that out. Battery temp sensor is located under driver's side battery tray.

The battery temp sensor sends temp readings to EVR (located in PCM).

The ASD relay sends line vlotage to the EVR.

The EVR takes the data from the battery temp sensor and ASD relay and determines alternator voltage output.

 

[Twisted Shifter]

I found it. some how, have no idea ... . the green wire (#20 pin)that comes from the PCM directly to the alternator was broken inside the black box that hooks to the alternator. I but the box off and ran the wires individually and all is well..... Thank you for the input.