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.
Circuit/System Testing
2006 Chevrolet Suburban C2500, 6.0 USECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition ON, with the brake pedal applied, observe the scan tool Brake Applied Output Signal parameter. The reading should be ON with the brake pedal depressed.
- If not the specified parameter, refer to Stop Lamps Malfunction .
- Ignition OFF, disconnect the harness connector at the automatic transmission shift lock actuator.
- Ignition OFF, test for less than 1.0 ohm of resistance between the ground circuit terminal B and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Connect a test lamp between the control circuit terminal A and ground.
- Ignition ON, command the scan tool BCM shift lock solenoid output control ON and OFF. The test lamp should turn ON and OFF as commanded.
- If the test lamp is always ON, test the control circuit for a short to voltage. If circuit test normal, replace the BCM.
- If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If circuits test normal, replace the BCM.
- If all circuits test normal, test or replace the shift lock actuator.
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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.