• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Ambient Light Sensor Signal Circuit | B2645 07 | B2645 03 | B2645 07 | B2645 03, B2645 07 |
The ambient light sensor is used to monitor outside lighting conditions. The ambient light sensor provides a voltage signal that will vary depending on outside lighting conditions. The body control module (BCM) provides a 10-volt reference signal to the ambient light sensor. The BCM monitors the ambient light sensor signal circuit to determine if outside lighting conditions are correct for either daytime running lights (DRL) or automatic lamp control (ALC) when the headlamp switch is in the AUTO position. In daylight conditions the BCM will command the DRLs ON. In low light conditions, when the headlamps switch is in AUTO position, the BCM will command the low beam headlamps ON.
Battery voltage must be between 9-16 volts.
• | DTC B2645 03 will set when the BCM detects voltage is low in the ambient light sensor signal circuit. |
• | DTC B2645 07 will set when the BCM detects voltage is above 10 volts in the ambient light sensor signal circuit. |
When DTC B2645 03 or B2645 07 is present, the ALC will default to ON.
• | The condition responsible for setting the DTC no longer exists. |
• | You issue a scan tool CLEAR DTCs command. |
• | A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred. |
Lighting Systems Connector End Views
⇒ | If the scan tool parameter is less than 7 volts, locate and repair an open, high resistance, or short to ground in the ambient light sensor signal circuit, or replace the ambient light sensor. |
⇒ | If the scan tool parameter is greater than 10.5 volts, locate and repair a short to voltage in the ambient light sensor signal circuit. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for BCM replacement, setup, and programming |