This has to be the most confusing electrical issue I have been through on my 2000 Dodge Ram 2500 gas. It all started with a open or short code on gps solenoid. Changed solenoid and it was fixed. Drove it for a few days and it came back. Got another solenoid, same issue. Wired in new connectors , same issue. Ended up changing computers. Now that code and limp mode is gone, I now have no fault codes other than wrong vin code. But, it gets worse. I have a no O/D light and high temp trans light on , even when cold, even before running. On all the time. I have no overdrive, and after a decent drive the brake light and abs light come on, still no fault codes. Ended up changing everything other than 3/4 solenoid and tc solenoid. Same issue. Only thing I found weird is I have a weak ground in the fuse box in the transmission relay. Believe it’s pin 3. To the left. If I attach that pin to a ground and plug it in it just blows fuse doesn’t change anything. Completely stumped. I have attached codes below.

 

Does your speedometer work?
The fault can be in the ABS and if your scanner doesn't display ABS faults you won't know.

P1765 Trans 12 Volt Supply Relay Control Circuit
Check/replace the transmission relay in the pdc. No power to the trans can give you all kind of codes. There may be a fuse for this also.

 

What year was the computer you installed?

 

[QUOTE=Moparite;3573430]Does your speedometer work?

The Speedo works, so what the dealer just told me is that since my truck is a 2000, and I put a used 1999 computer in it that they are not compatible. Some sensors in trans are different like the gps sensor. The 1999 also has brake controlled seatbelts which are why the brake lights are on as it doesn’t see a body control module or anything since my truck doesn’t have it. So I might be in the clear with a new computer, I hope lol. As for the short or open sensor codes it was a fuse in fuse box, but after changing it all codes would go away other than gps solenoid short. Then after That I changed the computer and got me to where I am now. No codes but O/D light and temp light, brake lights come on after a bit of driving. Hope new computer fixes it.