Shift Solenoid "A" Circuit Check - LT. Truck: Notes

Fig 1: Shift Solenoid "A" Circuit Diagram (Lt. Truck)

Courtesy of GENERAL MOTORS CORP.

Shift solenoid "A" is attached to the valve body and is a normally open exhaust valve. The PCM/TCM activates he solenoid by grounding it through an internal quad driver. Solenoid "A" (Blue) is on in 1st and 4th gears, but is off in 2nd and 3rd gears. When solenoid is on, it redirects fluid to act on the shift valves.

1. This test checks shift solenoid "A" and the internal transmission wiring harness for shorts.
2. This test checks for power, from the ignition switch through the fuse, to the shift solenoid.
3. This test checks circuit No. 1222 for a short to ground.
4. This test checks PCM/TCM's ability to ground or control the shift solenoid "A". If bidirectional Scan tester is not available, TCC may be activated by grounding ALDL test terminal "B" With ignition on and engine off.