Transmission won’t shift — GM vehicles
GM Check engine light on, transmission won’t shift — service bulletin ##01-07-30-002E
GM has issued a service bulletin ##01-07-30-002E to address a problem where the transmission won’t shift out of 2nd gear or transmission won’t shift out of 3rd gear. You’ll also have a check engine light and one or several of these trouble codes P0740, P0753, P0758, P0785, P0787, P0973, P0976, P1860, P2761, P2764 and P2769. The service bulletin affects the vehicles listed below.
Vehicles affected
2006 and Prior GM Passenger Cars and Light Duty Trucks
2005-2006 HUMMER H2
2006 HUMMER H3
2005-2006 Saab 9-7X; with 4L60-E, 4L65-E, 4L80-E or 4L85-E Automatic Transmission
Cause of transmission problem
GM has discovered that the most likely cause of the lack of shift is low voltage to the transmission solenoid power supply circuit. This is most often caused by the improper installation of an aftermarket electronic device like a remote starter or alarm system.
Fix for transmission won’t shift
With the ignition switch in the RUN position, use a voltmeter to test for battery voltage at the circuit fuse in the transmission solenoid power supply circuit. If you don’t see battery voltage at the circuit fuse, refer to a wiring diagram and backtrack to find the source of the voltage drop. The low voltage will cause all of the above listed trouble codes and cause a transmission won’t shift condition because the shift solenoids aren’t receiving the proper voltage.
If battery voltage is present at the fuse, inspect
the ignition voltage circuit between the fuse and the transmission for possible opens. If battery voltage is not present at the fuse, test for continuity between the fuse and the ignition switch. If NO continuity is between the fuse and the ignition switch, repair the open in that circuit. If you have continuity between the fuse and the ignition switch, the most likely cause is the ignition switch.
©, 2018 Rick Muscoplat
Posted on by Rick Muscoplat