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.
1996 GMC Cab & Chassis C2500, 5.7 R, AutomaticFACTORY OEM SERVICE PROCEDURE
Transmitter Functions Do Not Operate
- If condition of batteries is unknown, replace transmitter batteries with fresh batteries. If transmitter now operates, system is okay, If system still does not operate, go to next step.
- Connect jumper wire between remote keyless entry module connector C2, terminal "H" (Black/White wire) and connector C1, terminal "F" (Black wire). If all power doors lock and unlock, go to next step. If all power doors do not lock and unlock, go to step 4).
- Leave jumper wire connected. Operate a known-good transmitter by pressing a single button once. Disconnect jumper wire. If known-good transmitter now operates all remote functions, replace inoperative transmitter. If known-good transmitter does not operate all remote functions, replace keyless entry module.
- Disconnect program connector jumper wire. Check Black/White wire for a short to ground. If wire is shorted to ground, repair Black/White wire. If wire is not shorted to ground, go to next step.
- Measure voltage between keyless entry module connector C1, terminal "A" (Orange wire) and ground. If battery voltage is present, repair Orange wire and reprogram keyless entry module. If battery voltage is not present, replace keyless entry module.
Factory Service Tools
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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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