Starting my truck last week and it started to run rough and die or rev up and down a few thousand rpms just sitting. After I got going it was running rough and the engine lite came on. If I turned the key off and restarted the lite went out but still ran rough. In about 5 miles of driving it ran fine and no problems for the rest of the day. 2 days sitting and went out to start and same thing happened. THEN on the way home home from work on the freeway it just died at 70 mph. Coasted to side and sat for 20 minutes then it restarted agaain with no problems. 3 days sitting same M.O. as before but now on the way to work about 15 miles down the freeway at 70 it died again and would not start. Left it for the day and went back that afternoon to tow it as it still would not start. My independent mechanic says the PCM is dead and I need a new one. Could this be true and if so which years would work and where is the best place to get one?

 

If you have NOT disconnected the battery since that engine light came on, read the directions HERE to get the codes from the computer.
Any codes you get, post back here (post the numerical code).
And the answer to your question is: look for a PCM from 1991 to 1993. Perhaps one from 1994 to 1996 will work, but I can't verify (the "new" 5.2L Magnum came out in 1991, and it had 230HP. Starting in 1994, it was downgraded to 220HP, so I don't know what or why the changed something).
Post any codes, and let us know what happens.

 

as already suggested pull the trouble codes. Its code 12 your looking for. If you haven't disconnected battery in 50+ starts of truck and get code 12 then your PCM (computer) is losing power intermittently. I went through this in my 92 just a few weeks ago. There are a few solder joints in the harness running from relay/fuse box across to the PCM. These corrode and short. Eventually the shorting will kill your PCM. You may just need to repair the joints but in my case it didn't fix the problem. I replaced my PCM and now it doesn't die like that anymore but now I have a backfire condition at approx 1700 - 2400 RPM's under load. IE maintaining speed (60ish MPH). If I accellerate or decellerate its fine, if I rev in park its fine. I'm on second PCM (reman from NAPA) and still the problem continues. I'm at a total loss as truck ran fine (other than the loss of power to PCM) before PCM swap and nothing changed other than the PCM replacement that caused the backfire. I wonder if the year thing on magnums and PCM is related to my problem. Wonder if there is anyway to tell the year the PCM came out of. I assumed the number on the PCM would match it correctly. Any thoughts on that dodgerules86?

 

did some snooping... For my truck at least (PCM # 56027141) the part # only matches up to the year 1992 for both the dakota truck and a van (sportser or sportsman or something) with same engine. If you need a new PCM then you need to get the number off it. I had trouble finding the number. Remove pcm from vehicle, take front cover off. while peering into it the number is on lower right corner. Mine had enough dust on the clear coating it looked black, clean off that corner and look thru the clear coating to locate the PCM ID # stamped onto the circuit board thats under that clear coating.

 

how do I get the codes?? went to the tow yard today and disconnected the battery for 15 min. and kept the key on start for 20 secs. hooked it back up and no engine lite and would not start.

Do I need a new pcm and is so where and what do I want???

Thanks

Rod

 

When you turn key to on (not start) if the check engine light dont come on for 4 secs that means computer (PCM) is not getting power...

First check the wire solder joints in the wire harness. You will need to unwrap electrical tape starting by the relay box (black box driver side under hood) and following across firewall towards passenger side. I never could get anyone to tell me the wire color of the wire in question but I found 3 splices, blues wires, red wires and a group of two black and two gray wires. I fixed all 3 sets. Sets are 4 wires that join and are soldered together. I cut the joint out and used a short jumper wire and 2 wire nuts per splice to make the repair.

Also read this

http://dodgedakotas.com/boards/v8/7278.html

If you need a new PCM you can get remanufactured at parts store (schucks, NAPA, autozone, motion, etc). I spent $189 at NAPA after core ($100 deposit on core). All other stores I called for price where same or maybe $10 higher. I see online you can get em for $150 but I didn't want to wait on it.

 

read this too... when truck wont start turn key to on open hood and WHACK the PCM with your hand. You will hear hissing and clicking of sensors turning on and fuel rail charging. If so chances are your PCM is bad. If not then wire joints are bad. PCM located on passenger side. its that big black box with a 60 pin connector going to it.

https://dodgeforum.com/m_510758/tm.htm

Read that post for more history on my similar problem...