Transmission Limp Mode triggered after Eng/Tranny swap, electrical?
 

Does anyone have a wiring diagram for both the 1996 and 1999 Town and Country Transmission Controller, EATX Relay and Power Distribution Center they would share with me please?

I recently had a broken valve spring that ruined my 1996 Town and Country engine. I replaced the engine (3.8 to 3.8) and the transmission (41TE TO 41TE) as well as the 1996 engine harness and transmission controller with the 1999 ones. Everything worked and I only had to change the plug ends on a couple of sensors or change the sensors.

Upon retrospect I should have left the original transmission in there. Now I’d like to see if it is just a wiring problem without having to re-swap the transmissions and harness again.

It runs fine but is frozen in limp mode with the P1768, "relay output always off" DTC code. The P0700 generic transmission fault code is also present, because of the P1768 code.

The power distribution centers (fuse boxes) had some differences in fuse and relay locations so I swapped in the 1999 one for the 1996 one. The DTC codes multiplied, so I switched back to the 1996 fuse box and things returned to the way they were previously but still stuck in limp mode with the P1768 code. I put the 1996 transmission controller back in but it made no difference so I returned the 1999 Transmission Controller.

The only other thing I could do without the wiring diagrams is swap in the 1999 Body Control Module or computer and see if that makes a difference.

Any intelligent help other than “take it to a mechanic or the dealer” would really be appreciated. Thanks.

Only just started studying this stuff myself as I have an elec prob. From what I understand you can't just replace/swap the BCM without reprogramming the ECM, PCM etc etc as the BCM controls the security system. Perhaps some one will confirm or be able to help with your other prob. It just that you would have to visit a dealer anyway if you replace the BCM so why not get them to check the prob first without swapping it. Just a thought...

RE Reprogramming
 

Thanks for the info. That makes sense and I should have thought about all that the BCM controls in relation to the re-programming. Something is wired differently between the two model years... I am pretty sure of it but I can't trace it down.