Circuit/System Testing
WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Clear the DTC.
- Use a scan tool to monitor the Dimming Control Reference Signal data parameter in the BCM data list.
- If less than 0.33 volt, test the I/P dimming voltage reference circuit for a short to ground or an open/high resistance and test the stop lamp signal circuit for a short to ground. If the circuit/connections test normal, replace the BCM.
- If greater than 4.97 volts, test the I/P dimming voltage reference circuit for a short to voltage. If the circuit/connections test normal, replace the BCM.
- If the voltage is correct and all circuits/connections test normal, replace the headlamp switch.