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 DIAGNOSIS (SINGLE PAGE)ACCESSORIES & EQUIPMENTCOMMUNICATION DEVICESDATA COMMUNICATIONS - DIAGNOSTIC INFORMATION AND PROCEDURES (4 OF 4)DIAGNOSTIC INFORMATION AND PROCEDURESSCAN TOOL DOES NOT POWER UPCIRCUIT/SYSTEM TESTING
2024 GMC Sierra 2500 HD Denali Ultimate
Circuit/System Testing
2024 GMC Sierra 2500 HD Denali UltimateSECTION Circuit/System Testing
- Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 10 min for all vehicle systems to power down.
- Verify a test lamp illuminates between each of the X84 Data Link Connector ground circuit terminals listed below and B+.
- Terminal 4
- Terminal 5
- If the test lamp does not illuminate
Repair the open/high resistance in the ground circuit or ground connection.
- Go to next step: If the test lamp illuminates
- Ignition ON/Vehicle In Service Mode.
- Verify a test lamp illuminates between the B+ circuit terminal 16 at the X84 Data Link Connector and ground.
- If the test lamp does not illuminate and the circuit fuse is good
- Test for an open/high resistance in the B+ circuit.
- If an open/high resistance is found, repair the fault on the circuit.
- Go to next step: If an open/high resistance is not found
- Verify the fuse is not open and there is voltage at the fuse.
- If the test lamp does not illuminate and the circuit fuse is open
- Test for a short to ground in the B+ circuit.
- If a short to ground is found, repair the fault on the circuit.
- Go to next step: If a short to ground is not found
- Refer to the scan tool user guide.
- Go to next step: If the test lamp illuminates
- Refer to the scan tool user guide.
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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.