Hi everyone my name is Andrew and I'm brand new to the forum.  I was hoping you could help me with my ECM problem.

 

I have no idea what caused my ECM to fail..  Is this a common issue?  Do I just replace it and cross my fingers or do I need to investigate further?  The truck ran just fine until I pulled in my driveway (luckily) and it died.  I had it checked out and was told the microprocessor fried and the ECM is deemed unrepairable..    

 

Since I can't buy a new one (discontinued) do I buy a used one with no warrantee or do I get a reman unit?  If reman who do you recommend?  I've called a handful of remans companies and every place seems very shady with poor online reviews.  I'm moving my family back to Utah from Florida and I need this truck to get us there safely.  The thought of plugging in a new ECM and having it fail at any time with a big trailer in tow is really bothering me.  Any advise or suggestions would be greatly appreciated.  Thank you for your time,

 

Andrew     

edit:  Also my ECM looks to have been a reman anyway..  not sure if that matters but here’s a pic.  

Edited October 20, 20195 yr by Rot Box

There is a company in California that builds wiring harnesses for vehicles. You ship them your current one and they build you a new one. Can't remember their name. I'd have to look.

20 hours ago, pepsi71ocean said:

There is a company in California that builds wiring harnesses for vehicles. You ship them your current one and they build you a new one. Can't remember their name. I'd have to look.

Definitely would be interested in knowing.

Thanks guys.  Been out on business the last few days..   Dripley, I like the headlights they're just the cheap amazon specials with the stock size bulb however I am running an LMC Truck 'heavy duty headlight harness' which is powers the lights off of relays so they're a fair bit brighter than stock.   

Hey everyone.  I'm back with the same ol' problem..  The truck hasn't changed too much other than I swapped in a P7100/p-pump because I wanted the simplicity of mechanical injection.     

 

To recap.  The truck runs fine--GREAT in fact.  Then randomly I loose the tach, fuel pump, alternator stops charging, it stays in third gear (I'm able to shift it manually to second but not first) and sometimes I loose the oil pressure gauge.  I loose power to the VP44 as well which used to shut the engine off.  No codes aside from P1689 which is expected with the pump swap.  

 

I've inspected and tested the ecm/pcm grounds as suggested. I have inspected every plug, wire/ wire harness etc that I can find and everything looks just fine.  I've completed the W-T mod and checked ac ripple and that comes back good.  

 

Everything seems to point towards a bad cam position sensor, but I've changed that already.  Swapping back and forth between my old and new one doesn't make a difference...    

 

Do I haul it to the stealership or shop and let them work on it?  I'm out of ideas and I NEED this truck.  Thanks again for any help 

 

             

Edit:  I was able to get a few more codes off of my gauge cluster that none of the other scanners/code readers picked up:
 

P1693

P1694

P0230

 

Edited December 8, 20195 yr by Rot Box

Rot box the ECM outputs a 5 volt square wave at twice the engine RPM about 30 Hertz at idle. It is on the gray with black wire going from the engine harness to the cab harness. Pin 10 on a 1999. The signal tells the PCM the engine is running which  will turn on the alternator and powers the transmission  controls and also AC clutch. It is NOT the tach. The tach oil and temp are sent from the ECM to the chrysler CCD bus as coded messages. It may be possible to fool the PCM by wiring the cam sensor signal straight to it. I haven't  tested it. You could isolate the cam sensor from the ecm and supply the 5volts and ground from the PCM. Example  5 volts supplied to govenor  pressure  sensor in the transmission. Wait the sensor is gone because its p-pumped. You will need the harmonic balancer  with a notch and the sensor from a 12 valve. Same idea though.

Great work,  thanks you for the reply. I’m starting to think I’m in over my head haha.  
 

Ive been driving it for short periods of time.  The only codes at the moment are p1693 and p1694 

 

If I could get the transmission to work I could externally regulate the alternator and solve the charging issue...  then again I’d like it to just work the way it was designed to.  I don’t know if I’m dealing with a bad ecm, pcm or wiring harness at this point.  Oye this is frustrating 

Edited December 14, 20195 yr by Rot Box