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 MANUALSCHEVROLET2006SUBURBAN K2500, 6.0 UREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1681 (LIGHTING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC B2580CIRCUIT/SYSTEM TESTING
2006 Chevrolet Suburban K2500, 6.0 U
Circuit/System Testing
2006 Chevrolet Suburban K2500, 6.0 USECTION Circuit/System Testing
WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the X4 harness connector at the fuse block - underhood.
- Connect a test lamp between the control circuit terminal C3 and B+.
- Command the High Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.
- If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
- Ignition OFF, connect the X4 harness connector at the fuse block - underhood. Disconnect the harness connector at the high beam headlamp.
- Test for less than 5 Ξ© between the high beam headlamp 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.
- Command the High Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the fuse block - underhood.
- If the test lamp is always OFF and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the fuse block - underhood.
- If the test lamp is always OFF and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the high beam headlamp.
- If all circuits test normal, test or replace the high beam headlamp.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.