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 MANUALSCADILLAC2011CTS V, 2D COUPE, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ACCESSORIES & EQUIPMENTHEADLIGHTSLIGHTING SYSTEMDIAGNOSTIC INFORMATION AND PROCEDURESDTC B2645CIRCUIT/SYSTEM TESTING
2011 Cadillac CTS V, 2D Coupe, Standard
Circuit/System Testing
2011 Cadillac CTS V, 2D Coupe, StandardSECTION Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the ambient light/sunload sensor.
- Ignition OFF, scan tool OFF, doors CLOSED, test for less than 10.0 Ξ© between the low reference circuit terminal C and ground.
- If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module.
- Ignition ON, verify the scan tool Ambient Light Sensor parameter is greater than 4.65 V.
- If less than the specified range, test the signal circuit terminal D for a short to ground. If the circuit tests normal, replace the BCM.
- Install a 3 A fused jumper wire between the signal circuit terminal D and the low reference circuit terminal C. Verify the scan tool Ambient Light Sensor parameter is less than 0.196 V.
- If greater than the specified range, test the signal circuit for a short to voltage an open/high resistance. If the circuit tests normal, replace the BCM.
- If all circuits test normal, replace the ambient light/sunload sensor.
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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.