New to the forum postings, learned a lot reading your post, thanks.1991, D250, 5.9, 2WD, automatic. 68,000 mile.
Voltage reg. on firewall malfunctioned, overcharged and blew battery. Did not blow fuses, however lots of damage was done and since repaired. Replaced lamps, wiper motor, signal-wiper control-turn signal, battery, regulator, speed sensor.
Cranks and runs great however speedometer, odometer, cruise or overdrive do not work. Your thoughts & ideas would be greatly appreciated.

 

Probably fried the PCM. It isn't needed for the engine to run, but the side shows run off it.

Crap happens when you hard strap a 120 amp alternator to an unfortunate battery.

 

Thanks, I'll replace PCM as suggested and see what happens next.
Appreciate your suggestions and comments.

 

We're talking some bucks here unless you happen to find one at a wrecker that doesn't know it's value.

It would be worth the while to find a wiring diagram and make sure the affected functions are driven by the PCM as I suspect. 1991 had a couple of different versions, and there may have been some mods on yours.

 

I agree with Mr. Martin....do some wiring diagram research first before spending the money on the new PCM.

Your 91, is it Non-IC or IC? If it's IC, and has the PCM, then the PCM is a one year only unit. 92/93 PCM will not work.

 

I had an issue with no speedo, cruise, or charge, narrowed it down to the PCM. Took the well heeded advice to check wiring and found that one of the 12v wires to my PCM was toast. Repaired that and all functions work.
I would check this before dropping the coin on a PCM.

 

My 89 has cruise which doesn't work, but the point I'm trying to make is it might make sense to retro fit to early 90 or 89 without the PCM to get things working. Is your trans an A518 with lockup and overdrive working?

 

Hey Foghorn,
We want to be helpful, but we're just guessing what you drive. Most of us put a description of our ride(s) in our signature line. Go to your UserCP and dress it up a bit.

 

Hey, I greatly appreciate any and all comments, suggestions etc. I'll go to the user file and do some input. Thanks, I'm new at this forum discussions so please accept my omissions and lack of input.

 

No way. We'll just politely nag till you get up to speed.

 

Thanks, I'll check this out. Ideas appreciated.

 

Nagging is something I know very well, keep er going. I've had the truck in two highly recommended shops looking for bad/burn wires, connections etc. Spent hours myself, all good shape.
Ordered a Powertrain (engine) Control Module last week, just got word that Cardone no longer rebuilds my unit(79-8911). No one has ask if the injectors are IC or Non IC as yet. While looking around for a solution a couple old timers assure me it's the very small electric motors in the odometer & speedometer instrument cluster. I continue to think PCM??? Any suggestions where to find one or rebuild mine?

 

I don't know who recommended the shops, but this relatively primitive system ain't rocket science.

We're still guessing exactly what truck you have, ie early or late '91. They're quite a bit different. (nag nag)

With diagrams, and some sort of a guide, either the OEM powertrain control diagnostics manual (yep they exist, I have one for '93), or one of the professional computer driven shop systems.

One way to know if your PCM is alive is to pull the trouble codes. Turn the ignition key on, off, on, off, on... then watch the check engine light. It should display at least a 55. It may display other codes indicating either it's wacked and knows it, or what circuit is wacked.

The procedure and codes a re on the FAQ page under engine.

 

Okay, I'm headed out to do my home work. My UserCP and my initial post for help indicated my truck is a" Year 1991 Dodge D250" 5.9 Diesel, 2WD, original equip., 68,000 miles. Cheers and thanks!

 

early or late 91, non intercooled or intercooled . There was a considerable change in the middle of 1991 production.