I recently purchased a 1998 2500 4X4 with the 5.9L motor. Seller said it needed a new trans but I have discovered that not to be the case. It will drive just fine with a jumper in the trans relay slot. I have done a fluid and filter change. Fluid was not dirty or burnt smelling. Replaced the governor pressure sensor. Repaired the wiring on the 8 pin connector, they were all touching and melted together. I replaced the PCM with a reman. from All Computer Resource. The new computer cleared up the P0622 code issue but I am still stuck in limp mode. What types of issues will cause limp mode to appear? I cannot locate any other bad wiring or connections. Would the governor pressure solenoid and or the TCC and O/D solenoids cause this? I know the catalytic converter is broken inside and I plan on replacing it soon. Would that cause any issues like limp mode? I will also be replacing the O2 sensors. Any help is appreciated. Also does it matter if the trans fluid is not ATF+4? I was told by a transmission rebuilder that it does not matter? Also have the P0753 and P1765 codes.

 

A faulty 02 Simm box put my 46RE in limp mode, check the 02 wiring. Use ATF+4. Period.

 

ok will do. Thanks.

 

What is a simm box?

 

Simulator. Fools the PCM into thinking an O2 sensor is actually plugged in.

 

Gotcha, thanks for the info.