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Test Description

WARNING: This page is about a different car, the 2004 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.

The number(s) below refer to the step number(s) on the diagnostic table.

  1. 2:  Tests ambient light sensor data using a scan tool.
  2. 3:  Tests the ambient light sensor data with the sensor disconnected. The scan tool will display ambient light sensor voltage as 0 volts with the sensor disconnected.
  3. 4:  Tests the ambient light sensor data with a jumper wire between the reference and signal circuit. The scan tool will display ambient light sensor voltage between 3.5-4.5 volts with the sensor jumpered.
  4. 5:  Tests for a short to voltage in the DRL ambient light sensor low reference circuit.
DTC B2648

Step Action Value(s) Yes No
Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics 
Connector End View Reference: Master Electrical Component List
1 Did you perform the Lighting System Diagnostic System Check? - Go to Step 2  Go to Diagnostic System Check - Lighting Systems 
2 
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Apply a bright incandescent light to the ambient light sensor.
  4. With a scan tool, observe the DRL Ambient Light Sensor parameter in the BCM data list.
Does the scan tool indicate that the DRL Ambient Light Sensor parameter is within the specified range?		 0.1-2.5 V Go to Diagnostic Aids Go to Step 3 
3 
  1. Turn OFF the ignition.
  2. Disconnect the ambient light sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the DRL Ambient Light Sensor parameter.
Does the scan tool indicate that the DRL Ambient Light Sensor parameter is less than the specified value?		 0.1 V Go to Step 4  Go to Step 9 
4 
  1. Turn OFF the ignition.
  2. Connect a 3 amp fused jumper wire between the 5 volt reference circuit of the ambient light sensor and the signal circuit of the ambient light sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the DRL Ambient Light Sensor parameter.
Does the scan tool indicate that the DRL Ambient Light Sensor parameter is greater than the specified value?		 3.5 V Go to Step 5  Go to Step 7 
5 
  1. Disconnect the fused jumper wire.
  2. Measure the voltage between the DRL ambient light sensor low reference circuit of the ambient light sensor and the signal circuit of the ambient light sensor.
Does the voltage measure less than the specified value?		 5.0 V Go to Step 10  Go to Step 6 
6 Test the DRL ambient light sensor low reference circuit of the ambient light sensor for a short to battery positive voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 11 
7 Test the DRL ambient light sensor low reference circuit of the ambient light sensor for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 8 
8 Test the signal circuit of the ambient light sensor for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 11 
9 Test the signal circuit of the ambient light sensor for a short to battery positive voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 11 
10 Inspect for poor connections at the harness connector of the ambient light sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 12 
11 Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 13 
12 Replace the ambient light sensor. Refer to Daytime Running Lamps (DRL) Ambient Light Sensor Replacement .
Did you complete the replacement?		 - Go to Step 14  -
13
IMPORTANT: Perform the BCM reprogram procedure. Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System.
Replace the BCM. Refer to Body Control Module Replacement in Body Control System.Did you complete the replacement?		 - Go to Step 14  -
14
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?		 - Go to Step 2  System OK
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