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 Low Voltage
DTC B2645 07
-
Ambient Light Sensor Circuit High Voltage
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 between 1.4-4.5 V depending on outside lighting conditions. When the headlamp switch is in the AUTO position, 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 or automatic lamp control. In daylight conditions, the BCM will command the daytime running lights ON. During low light conditions, the BCM will command the low beam headlamps ON.
Conditions for Running the DTC
Ignition ON
Conditions for Setting the DTC
B2645 03
The BCM detects a voltage below threshold on the ambient light sensor signal circuit.
B2645 07
The BCM detects a voltage above threshold on the ambient light sensor signal circuit.
Action Taken When the DTC Sets
The condition for setting the DTC is no longer present.
Conditions for Clearing the DTC
The condition for setting the DTC is no longer present.
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 Programming and Relearning for scan tool information
Circuit/System Verification
Ignition ON, observe the scan tool Ambient Light Sensor parameter. The reading should be between 1.4-4.5 V and change with ambient light changes.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the B10 ambient light/sunload sensor.
2. Ignition OFF, scan tool disconnected, interior lamps OFF, doors CLOSED, test for less than 10 ohms between the ground circuit terminal 6 and ground.
• If greater than the specified value, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Ambient Light Sensor parameter is greater than 4.65 V.
• If less than the specified range, test the signal circuit terminal 5 for a short to ground. If the circuit tests normal, replace the K9 BCM.
4. Install a 3 A fused jumper wire between the signal circuit terminal 5 and ground. Verify the scan tool Ambient Light Sensor parameter is less than 0.196 V.
• 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 K9 BCM.
5. If all circuits test normal, replace the B10 ambient light/sunload sensor.
Component Testing
Static Test
1. Ignition ON, observe the scan tool Ambient Light Sensor parameter. The reading should be between 1.4-4.5 V and change with ambient light changes.
2. Test the B10B Ambient Light/Sunload Sensor by varying the ambient light while monitoring the sensors voltage output.
3. Verify that the voltage output is within the range of the specification.
• If not within the specified range, replace the B10B Ambient Light/Sunload Sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Headlamp Automatic Control Ambient Light Sensor Replacement Service and Repair
* Control Module References Programming and Relearning for BCM replacement, programming and setup