B2645
DTC B2645
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC B2645 03
-
Ambient Light Sensor Circuit Voltage Below Threshold
DTC B2645 07
-
Ambient Light Sensor Circuit Voltage Above Threshold
Diagnostic Fault Information
Circuit/System Description
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 5 V 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.
Conditions for Running the DTC
Battery voltage must be between 9-16 V.
Conditions for Setting the DTC
B2645 03
The BCM detects voltage is below 0.196 volt in the ambient light sensor signal circuit.
B2645 07
The BCM detects voltage is above 4.9 volts in the ambient light sensor signal circuit or if the ambient light sensor ground circuit is open.
Action Taken When the DTC Sets
The automatic lamp control will default to ON.
Conditions for Clearing the DTC
* 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.
Reference Information
Schematic Reference
Headlights/Daytime Running Lights (DRL) Schematics Headlights/Daytime Running Lights (DRL) Schematics
Connector End View Reference
Component Connector End Views Connector End Views By Name
Description and Operation
Exterior Lighting Systems Description and Operation Exterior Lighting Systems
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the ambient light sensor.
2. Test for less than 5.0 ohms between the ground circuit listed below and ground.
* Ambient Light Sensor terminal C - CJ2
* Ambient Light Sensor terminal B - w/o CJ2
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Ambient Light Sensor parameter is greater than 4.5 V.
• If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the BCM.
4. Install a 3 A fused jumper wire between the signal circuit terminal listed below and the low reference circuit terminal listed below. Verify the scan tool Ambient Light Sensor parameter is less than 1.0 V.
* Ambient Light Sensor terminals A to B - w/o CJ2
* Ambient Light Sensor terminals D to C - CJ2
• 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.
5. If all circuits test normal, test or replace the ambient light sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Ambient Light Sensor Replacement Service and Repair
* Control Module References Control Module References for BCM replacement, setup, and programming