GMC Repair: No reverse, electric solenoids, forward gears

Question
I have suddenly lost reverse in my 1994 GMC Sierre Z71. All the forward gears seem to be working properly. What should I check first?

Answer
Most newer transmissions are computer controlled by electric solenoids mounted on the valve bodies within the transmission.

If your transmission has a large electrical plug going into the transmission with 5 or more wires this would be an electronic transmission. In this case:

1. You could have a solenoid problem within the trans.

2. A thermal sensor fault within the transmission.

3. A fault within the vehicles computer.

4. Major component failure(s) within the reverse mechanics of the trans.



Pull the dipstick and see if the fluid smells BURNT and or has a DARK COLOR to it. If it DOES, The trans will in most cases have to come OUT for repair.


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