Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Ambient Light Sensor Signal | B2645 | B2645 | B2645 | -- |
Ambient Light Sensor Ground | -- | 1 | -- | -- |
1. Daytime Running Lamps Inoperative |
The ambient light sensor is used to monitor outside lighting conditions. The ambient light sensor provides a voltage signal that will vary between 0.2 and 4.9 volts depending on outside lighting conditions. The body control module (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. During low light conditions the BCM will command the headlamps ON. Any function or condition that turns on the headlamps will cancel DRL operation.
Important: This diagnostic procedure assumes that the front turn signal lamps are operating within specifications. If the front turn signal lamps are inoperative, diagnose the turn signal lamp malfunction before proceeding with the following diagnostic. Refer to.
Headlights/Daytime Running Lights (DRL) Schematics
Lighting Systems Connector End Views
⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
⇒ | If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the BCM. |
⇒ | If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for BCM replacement, setup, and programming |