Engine/Transmission (1994 - 1998) '96 charging system problems

[Rescue Ram]

Rog and others,

Thanks for the ideas. I had thought of converting to a conventional external voltage regulator. I am concerned that if one function of the PCM is bad, then others may follow in short order. I justify this by the grid heater problems that I have been experiencing. I hope that the PCM does fix the problem. I want the old girl up and running... she is my favorite. :{ I'll give an update when I have it. Thanks for all of the help.



Brian Z. Oo.

 

[Missouri Mule]

Rescue Ram,

Battery temp sensor is under driver's side battery, it sends temp readings of the battery to the PCM. The ASD relay is turned on by the engine speed sensor it sends line voltage readings to PCM which than determines alt output.

Battery temp sensor does not have anything to do with grid heaters( intake temp sensor sends pcm data for them).



It seems to me that alternators tend to overcharge batteries when on their way out.



I have Red optimas(3-4 yrs) doing fine! Many members use them.

 

[Rescue Ram]

Good news

Finally!

28 days after it was dropped at the shop, the new PCM is in. The flickering is gone entirely, the charge guage has stabilized, and the heat grids are working normally. Even better, I got a super neato $600 paper weight out of the deal



An interesting observation- When bought this truck new, I NEVER had any sign of the temp guage cycling. The guage showed a consistent 175 F. At 72,000 miles, it developed the guage swing from 150 to 190. I spent quite a bit of time chasing my tail on that, tried 3 different thermostats, and decided that maybe it in-fact was a normal operation. With the installation of the new PCM, the temp guage is again stable, running 175F. Maybe its just a coincidence, but I thought I would mention it anyway.



Thanks again for all the help and suggestions.



Brian Z Oo.

 

[Evil Otto]

brian my 96 does the same thing from time to time when it is real cold. you said u live in fl. so your heaters should on come on. but they will when cold. if you stop in a drive through and shut off the truck to hear the box and restart the heaters will restart and go through a warm cycle even know thr truck is a full temp. when i first got the truck is was in the winter and i did the same thing the dam thing did not have 3000 miles on it. i was ****** if you drove early mopars for the 60's and 70's you know how bad there voltage regulators were. the amp guage would dip with the turn signual on. but i found out that is was the heaters starting again. for your cooling temp dipping that is normal depends what stat cummings put in it at the factory. mopar has an updated stat for that it will hold steady at 180 deg. good luck with your problem. what your talking about is realted to cold temp hope you did not but a pcm for nothing. ed

 

[Rescue Ram]

Evil Otto,

Thanks for your suggestions. Please reread the thread. I live In Colorado, and the light flickering is not a result of the heat grids. The replacement PCM has fixed the issues I was having with my truck (again, please reread the entire thread for a description of the problems). I am aware of the updated t-stat part. As I mentioned, I used three of them before I quit trying to solve the cycling problem. I was only pointing out observations I made about the functioning of the new PCM. The temp guage issue may or may not be related; just something for others to think about.

Brian Z. Oo.

 

[Howard Durand]

Just a suggestion, it may be overkill but in view of the extra load you have installed, you might want to connect another cable between the two batteries to even out the current draw between them.

Glad the new PCM solved the problem.

 

[dennyhare]

To the rear of the driver's side battery where the ground wires come out of the PCM to a small flat junction plate, take the screw that holds the plate to the fender well, scrape clean and run a small ground wire from under the plate where the screw fits into the fender well to any place on the engine. Wy '96 did the same thing. The speed sensor loses ground to the fender, so the PCM can't get the signal from the speed sensor. Guaranteed 10 minute fix.