Hi guys I recently had my car give me the gear box fault code I got the code read and it's saying p0778 to do with solenoid b however I have now had a new gear box and transfer box and yet the fault is still there is it possible that the TCM has died I've had it out and it looks in very good condition is there a way of testing it, it's driving me mental any help would be much appreciated.

 

A Model and Year would really help!!!!!!!!!!!!

Did you clear the DTC when you installed the replacement gearbox??????
The TCM does NOT know that the gearbox has been replaced.

Here is a JATCO DTC guide.

bob gauff

 

Hi and sorry its a 2002 x type 2.5 AWD automatic and yes i cleared the fault. over the weekend I resistance and continuity checked the high resistance circuit all passed so accordingly every thing points to a faulty TCM although there doesn't seem to be any visual damage its now all I can change with fingers crossed

 

Ok replaced the tcm and I still have this damn code any ideas anyone?

 

I had the same code on my 2006 X-Type 3.0 108K miles. it turned out to be an electrical problem - the battery had been replaced recently and it appears the old battery had leaked some on the wiring harness underneath - replaced section and code cleared - good luck! J

 

It does seem electrical did you replace the whole harness ie from transmission to TCM to ECU?

 

I just repaired the wires underneath the battery tray that had some corrosion on them reset the codes.