Circuit/System Testing
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2007 GMC Yukon XL, 2007 GMC Yukon, 2007 Chevrolet Tahoe, 2007 Chevrolet Suburban, and 2007 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition ON and clear the DTC. Use the scan tool Incandescent Dimming output control to adjust the dimming level of the I/P lamps from low to high.
- If the lamps cannot be controlled with the scan tool, replace the BCM.
- Monitor the Dimming Control Signal voltage parameter in the scan tool BCM data list while adjusting the dimmer switch from high to low.
- If the voltage is above 4.97 volts, test for a short to voltage in the I/P lamp dimmer switch signal circuit.
- If the circuit/connections test normal, replace the headlamp and panel dimmer switch.
- If the voltage drops below 0.10 volt, test for a short to ground, open, or high resistance in the I/P lamp dimmer switch signal circuit.
- If the circuit/connections test normal, replace the headlamp and panel dimmer switch.