Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Shift Solenoid "A" Circuit Check: Notes
Shift solenoid "A", also referred to as 1-2 shift solenoid, 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" (Gray) 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.
- This test checks shift solenoid "A" and the internal transmission wiring harness for short circuits.
- This test checks for power, from the ignition switch through the fuse, to the shift solenoid.
- This test checks circuit No. 1222 for a short to ground.
- 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.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.