K 2500 Truck 4WD V6-262 4.3L VIN Z (1992)
Shift Solenoid "A" Circuit
Circuit Description:
Shift solenoid "A" is attached to the valve body and is a normally open exhaust valve. The PCM/TCM activates the solenoid by grounding it
through an internal quad driver. Solenoid 'A" is "ON" in 1st and 4th gears, but "OFF" in 2nd and 3rd gears. When "ON," the solenoid redirects
fluid to act on the shift valves. Solenoid "A" is usually blue in color.
Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This procedure checks shift solenoid "A" and the internal transmission wiring harness for shorts.
2. This check is for power to the shift solenoid from the ignition through the fuse.
3. The third test checks CKT 1222 for a short to ground.
4. This test checks the PCM/TCM's ability to ground or control shift solenoid "A".
Diagnostic Aids:
Check all connections especially those at the transmission pass-thru connector. See: Powertrain Management/Computers and Control
Systems/Testing and Inspection/Symptom Related Diagnostic Procedures/Intermittent Condition
