2001 GMC Jimmy SLE 6Cyl4.3L - Transmissions & Drivetrains
Won't shift automatically but will manually while affecting idiot lights and speedometer.
Only 100,000 city miles. Service, ABS and Brake light come on when in gear while the speedometer doesn't want to work. When it does the lights go out. This definitely corresponds to the rpms and shifting of the transmission. When it tries to shift automatically, the lights blink off and the speedometer tries to work. Seems to shift manually ok but not great. Electrical or tranny issue?