Is the auto transmission of your 80 Series having problems or not shifting into one of the gears? Is the OverDrive light on the gauge cluster flashing? If so, then a trouble code has been stored. Here’s how to enter diagnostic mode to read the code:
Here are the diagrams referenced in the video:
My Number 2 Shift Solenoid was bad. There are a total of 4 solenoids. Here’s a diagram of their location, as well as TCM, Speed Sensor and TPS sensors:
