Transmission Swap = PCM issues

[03Cumminsguy]

Ok. I'm new here and have an issue I've been stumped on for 2 months. I bought a 99 24 valve that was a 5 spd truck, it came with all the automatic stuff from another 99. I have everything installed and all is good except the PCM. The PCM is the 56040199 which is verified a 99 automatic PCM, however when starting the truck, it acts like a 3rd gen with a transponder key. It starts, runs for 3 secs and dies.... It did that 3 times and now a no start and I know 2nd gens didn't have a transponder key.  It has full communication with the obd2 connector but no CEL's and now a no start. I "borrowed" the PCM out of my 00 which starts, runs and drives the truck but I have no communication with the obd2 connector, no lockup and no overdrive. Any advice would be awesome.  Thanks, it's been a hell of a project and I just want it done lol

[CSM]

Good looking trucks.  I am not 100% sure on this, but I thought that if it was the right year/trans PCM it should swap across without major issues.  It could be a bad pcm or need reflashed.  

Perhaps somebody else will chime in with some experience.  I wonder if the 99 will run your 2000.  

[03Cumminsguy]

Thanks for the reply. I just put the 99 PCM in both trucks and it's acts like there is a anti theft thing going on... Just cranks and no cel's. I put the 00 PCM in and it starts right up but no communication to the trans or obd2. Btw.... The pics are the befores and afters. Same truck lol

[Mopar1973Man]

Actually the 24V 2nd Gens had a security key fob and that isn't the PCM exactly. The central timer under the dash is the controller for the security system but typically it dead if set/armed and never fires.

I would have to say to check fuel pressure and basics. Is the lift pump even working?

Edited October 31, 2015 by Mopar1973Man

[03Cumminsguy]

Everything is good and operates fine if I put the PCM out of my 2000 into it.... Fires up, runs and drives, but no lockup, overdrive or obd2. If I put the 1999 PCM back into the truck, cranks but won't start, but has obd2. But to answer your questions, yes lift pump works, brand new vp44. It's like a electronic factory anti theft shut down issue, definitely a PCM issue

Edited October 31, 2015 by 03Cumminsguy

[gassernomore]

I can have this same issue if the key fob gets pressed while the door is open. It will crank for ever and not start, To fix the problem, I take the key out of the ignition and press the unlock and then it fires up. First time it happened it drove me insane checking every thing out. Then dumb luck and figured the key fob was the problem.

[03Cumminsguy]

Yeah I don't have a key fob for it. I'm thinking the PCM out of this other truck had the higher security system but my truck doesn't so that's where I'm kinda lost. I need to figure out which wires to cross to get past it.

[Me78569]

Mike,

 

Didn't Ed do a post of an issue like this having to do with the central timer module?

 

 

[Mopar1973Man]

Mike,

 

Didn't Ed do a post of an issue like this having to do with the central timer module?

 

 

Actually the 24V 2nd Gens had a security key fob and that isn't the PCM exactly. The central timer under the dash is the controller for the security system but typically it dead if set/armed and never fires.

I would have to say to check fuel pressure and basics. Is the lift pump even working?

That's why my original post I remember that post too. I'm almost sure the central timer has the security feature. The only thing I can think off is having the whole thing reflashed.