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.
Gear Selector Module (GSM)
The gear selector assembly is positioned in the center console and is mechanically connected to the transmission by a cable which moves the gear valve in the valve housing. The gear selector module (GSM) is positioned on the top panel of the gear selector assembly.
The gear selector module (GSM) receives gear position signals from the transmission control module (TCM) via serial communication. The transmission control module (TCM) receives the present gear position from the gear-shift position sensor. The LEDs in the top panel indicate the selected gear to the driver. The gear selector module (GSM) communicates serially with the central electronic module (CEM). The central electronic module (CEM) sends a signal to the gear selector module (GSM) to activate the shift-lock. The power supply and ground for the shift-lock solenoid are directly connected to the gear selector module (GSM).
The "W" switch in the gear selector assembly top panel is positioned on the printed circuit board for the gear selector module (GSM) and activates Winter mode. The gear selector module (GSM) checks the back-up (reverse) inhibitor function based on the vehicle speed signal from the transmission control module (TCM).
There are diagnostics for the gear selector module (GSM). Diagnostic trouble codes (DTCs) are stored in the transmission control module (TCM) in the event of a fault.
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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.
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