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.
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HOMESERVICE MANUALSGMC2024SIERRA 2500 HD DENALI ULTIMATEREPAIR AND DIAGNOSISBODY & FRAMEIGNITION SWITCH/STEERING LOCKIMMOBILIZER SYSTEMDIAGNOSTIC INFORMATION AND PROCEDURESDTC P1631CIRCUIT/SYSTEM VERIFICATION
2024 GMC Sierra 2500 HD Denali Ultimate
Circuit/System Verification
2024 GMC Sierra 2500 HD Denali UltimateSECTION Circuit/System Verification
- Ignition - On / Vehicle - In Service Mode
- Verify there are no DTCs set related to the following component/system: K89 Immobilizer Control Module
- If other DTCs are set
- Go to next step: If no other DTCs are set
- Perform the SPS function: Z1 Immobilizer Function - K9 Body Control Module Refer to: Immobilizer System Component Programming
- Engine - Crank
- Verify the function: Engine = Running
- If the engine does not start
Perform the SPS function: Z1 Immobilizer Function - K20 Engine Control Module Refer to: Immobilizer System Component Programming
- Go to next step: If the engine starts
- If the engine does not start
- All OK.
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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.