Got a new battery, alt. speedo not working ,amp gauge low,tac dead 1992 d350 diesel

 

Only way I know of is to swap it with one that you know is working.
I've ran into a few dealer diagnosed bad pcms, none had a bad pcm.
The pcm is a tough unit that rarely fails, the problem is usually a bad connection.
The pcm connector pins are very flimsy and the female ends are prone to enlargement that creates a bad connection.

 

I may be wrong, but I think years ago when I worked at the dodge dealer I had one where none of the gauges would work, but it would start and run. I ended up putting on a crank sensor and all the gauges started to work. Something about using the crank sensor to let the computer know that the engine is running, not for timing or anything like that. I'm pretty sure it was around a 90 model, old body style dodge 350 dually. Might be something to check into before you shoot a pcm on there. Actually go to this site and they might be able to help you out more......I'm a member there and it has a lot of good techs floating around, it is....

www.flatratetech.com

Just explain your problem and they will post back any info or ideas they have. I'll also go and look into it.

 

hey jcb, I went to the site and posted it, you click on that link, don't mind the Ford Technicians hub thing on the main page, it's for all techs. Click on message forums and then dcx automotive advise, you'll see it says 92 dodge d350 diesel question, click it and watch for people to post with ideas and such. Will the truck start and run? Or is it dead? More info for these guys the better.....these are real life, in the dealer techs so they can be a real help, I know, I have helped many on this site with cadillac problems....yeah, that's my poison...email me and let me know any more info or if you fixed it.

Shawn

 

your pcm will be one of three things- It will have power and be smart, by smart i mean it will process everything and everything will work correctly, or it will have power and be dumb where it wont process information and things wont work right, or three your whole pcm is just falt out bad and doesnt have power at all. Like what was stated earlier I would look into the connectors being bad. Or if you take it to a dealer they can use a scan tool and pull up any fault codes that it might have logged. I would not just go and swap the pcm out becasue there can be an underlying problem that caused it to not work properly. There are really very few ways to test one unless you are a dealer, just dont go poking around your pcm with a test light looking for power because pcms can't handle amps and test lights dont have enough internal resistance to prevent you from frying your pcm. A lot of times pcms, ecms, or any kind of controller will have an led light on there flashing green if its good, and no color at all if its bad but i dont think that is the case if i were you i would look for other possible reasons before buying a pcm

 

First gen PCM's don't have an indicator light and they are a common failure. I know of 4 that died, my 93 just had a bad tach lead, my sons 92 had the charging system, cruise, AC, heater blower all quit at the same time. A new PCM and all was working. Replacements can be had at the dealer for about $250

 

Your list of problems sounds to me like the sensor on the front of the engine has failed not the pcm. The sensor reads the crankshaft revs and tells the pcm the when the engine is running which then turns on the field current to the alternator which then begins to charge.This works the same all the way up to at least the 95 models. The engine will start and run fine but the computer does't know it is running which is why the tach does not read and the charging sytem does not fuction. If you replace the sensor (about $53.00) and things still do not work then move on to the pcm . Rattlerbob

 

heater grid not working also