'92 Dodge Cummins with no charge from the alternator
 

Hey guys,
Already posted this in the Dodge 1st gen section, figured I'd post it over here too. I'm getting no charge on the batteries. Tried replacing the voltage regulator, the crank position sensor, and the alternator. Still not getting a charge on the batteries, wondering what else I can do to test or try and get it fixed. Only other thing I can think of is the engine management computer thing. Thanks for any help you guys can give me.

I dunno how far this goes back if its on yer truck or not but my 01 has a battery temp sensor under the drivers side battery, if the battery is hot it wont charge no way

Mine does not have that sensor, but thanks for the idea.

Check the engine speed sensor (mounted by the harmonic balancer). Probably a little crud caked on it.

Already cleaned and adjusted that, still didn't work. Got a new one and replaced it, still doesn't charge. Replaced the alternator after that, still doesn't charge. Starting to wonder what's wrong with it and what can I test with my meter to eliminate things.

Obviously the battery is charged enough. Perhaps do a load test on it anyway??

With the truck on and running and the headlights on, voltage on the battery is 11.9, should be more like 13.8. Left the new alternator and crank sensor in and bypassed the voltage regulator section by shorting the field to ground, and the system did charge. So something isn't telling the alternator to charge, so at this point I've replace a $180 alternator and $120 crank sensor for no good reason. Seems that perhaps the computer or one of it's sensors that tells it to tell the alternator to charge isn't working properly. Anyone have any ideas of quirky stuff the the Powertrain Control Module might be looking for?

our 92 had the same thing happen. the problem is somewhere in the PCM circuit or wiring. I gave up on trying to diagnose the PCM and added an extermal electronic regulator. The same one used on dodge and chrysler for about 30 years. If you need help I can send information on how to do the change. We also had a problem with the overdrive shift.

are you sure it has a voltage regulator most of these trucks had computer controlled field for adjusting charging voltage

Mine already seems to have an external, which might be what the PO already did, it does have crimp butt splices on the connector that goes to the voltage regulator. Seems the only thing that the PCM is doing right now is sending 12V to the regulator and field winding to energize it during key on operation. Aside from that, the other field wire goes to the regulator and it's grounded with the screws that attach it to the fenderwell. My OD was having an issue too, so it's wired to a toggle switch to kick into OD when needed, already had to bypass that system so I'm guessing the PCM is pretty much FUBAR. The wait to start light is on and off at odd times. Off during start up, and then sometimes on while running. Any idea where I can find another PCM to remedy some of the things instead of continuing to bypass things? I know for now how to bypass the PCM system and make it work, but right now it's not even working with the external transistorized regulator, I'm guessing it may need a better ground wired to it.

I just got the factory manual on CD from Geno's garage so if schematics would help you I could send them to you. Like I said before I gave up on trying to diagnose and fix the pcm system and did the bypass thing. If the external regulator has power to one lead lead and grounding the other makes it charge the regulator has to be bad. Some auto parts stores can test the regulator to make sure though.

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If you want to automate the OD shift you can add an adjustable normally open hobbs switch to one of the ports on the tranny and set it to whatever speed you want it to engage, That is what I did with ours. Then the toggle switch can be used to disable it when you don't want it to work

Does your OD work normally? If not, then the PCM is not getting voltage. Give me a call and I'll walk you through it. Went through it on my 91.5.

The OD wasn't working when I got the truck, replaced the speed sensor and took the TPS loose to test, it still wouldn't shift. So I wired a toggle switch to the ground side of the solenoid. When I want OD, I flip the switch, allows me to shift it when I want based on load, how hard I'm accelerating, or if I'm cruising and want to grab it early. I will be down where I can put my hands on the truck on Sunday, is it ok to call then? I really appreciate all the help. As for the external regulator being bad, I can have them try and test this one as well. Drives ya crazy that you go through all these parts and replace really expensive ones to find out they weren't the problem at all. Oh well, guess I have some spares now.

Updates?? :pca1:

trans temp switch in the 1st gen diesels was a huge culprit in the no OD situation
93 and older use a switch and 94 and newer use a sensor (both plug in and thread in and look identical) make sure you get the right one

No real updates, haven't had time to work on it, trying to get moved currently, but did drive it from Orlando to Jacksonville FL, about a 2 hour trip without any problems, only had to use the headlights at the very end of the trip and had enough battery for that chore. But as soon as I figure out anything or have them try and test the voltage regulator, I will update the thread. Thanks again for the help. As for the temp switch/sensor deal, I'm wondering why they use so many sensors that are known to go bad for something like OD. I guess they want to really know what's going on everywhere to get the thing shifting right. As before though, the toggle switch is still working wonders on the OD problem :)

A beer bets your PCM is not getting voltage from the battery to turn it on, therfore, the PCM can not tell the voltage regulator to take over control of the field. Give me a call and I can go over the PCM pin out and we'll see if your getting voltage where you need.

After I got voltage to my PCM, we found that the PCM was toast, giving 5v to the TPS and provind 5v on the sensor pin, thus the transmission would never go into OD on its own. I did the switch thing for a bit and fixed it with a 5 speed. . . . .

Not too particularly worried about the OD right now, but if the no voltage to the PCM is causing all these problems, that will be what I need to fix. Still haven't had a chance to go through and try some of the suggestions offered yet, but I'll be glad to give you that beer if that fixes the trouble, I should have some time Friday to work on it, off of work that day, so I'll give you a ring for sure. Thanks again for all the help guys.

Updates please.

Please update.

Going to close down the thread for now. Thread starter can reopen.

Sorry I couldn't get on to update things, been in the process of moving and then didn't have internet access until yesterday. Still no progress on the situation though. I'm going to try calling Diesel Nut Motorsports and see what we can figure out about the PCM, it seems to be having some issues, now the speedo is going haywire too and it's a nearly new sensor, replaced it about 500 miles ago. So at this point, not much progress and the frustration with electrical demons continues. My neighbor is a mechanic and is going to help me out some too, but I'm in need of some good Dodge diesel electrical troubleshooting help for sure. Thanks again guys.

No problem.

Please update. :pca1:

I'm off work today, hopefully gonna work on it and see where I can get today. I'll post an update later on and let you know what happens. Thanks again guys.

Updates??

Please update.

Going to close the thread for now. Can reopen and update.