Okay guys I just bought this gmc jimmy last Friday, drove it home and it started upon its mission to its own death. First transfer case is leaking fluid from the vent tube, already know that its the seal between the two. that will get replaced if I can figure out my transmission problem.


Seems to be that the transmission is starting in second gear and I have no overdrive anymore you can tell the truck is gutless 55% throttle to get the vehicle moving I have pulled the check engines codes which are all transmission related.


P0740- torque converter clutch circuit
P0753- shift solenoid A electrical
P0758- shift solenoid B electrical
P0785 Shift/Timing Solenoid


Now, I have checked into this problem and most people are saying this is related to the ignition switch not function properly and not sending power to fuse 24. I have checked power at that fuse with the key in the on position and I have no power at the fuse if I shift into reverse I get around 10.00 volts same with drive 3 2 1 they all pull the same power so Im at a stand still currently Im not sure where to go with this.

 

Probably a bad ignition switch, when both shift solenoids are off you get third gear only and no automatic shifting. Highly unlikely every solenoid in the trans went out at the same time, no power to the trans is usually the culprit for multiple solenoid codes. The contacts in the switch burn and carbon up, when there is a load on the circuit the voltage drops. Reverse the solenoids are off, reverse is controlled solely by the manual valve.


Pull the cover off the column to access the switch wires, with the ignition on the pink, orange, and pink/white (or solid white) wires should have power. If one has none or low voltage you found the issue, new switch time. If they all have full power and the fuse still reads low/no voltage you got a bad wire or connection somewhere between the switch and the fuse.