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Test Description

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

  1. 2:  The normal operating voltage of the ambient light sensor (photocell) is 0.5-4.5 volts.
  2. 3:  This step determines if there is a problem with the signal circuit of the ambient light sensor.
DTC B2647

Step Action Value(s) Yes No
Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics 
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2 
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the PHOTOCELL VOLTAGE data parameter in the LAMP STATUS data list.
Does the scan tool indicate that the PHOTOCELL VOLTAGE parameter is within the specified range?		 0.5-4.5 V Go to Testing for Intermittent Conditions and Poor Connections 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. Probe the signal circuit of the ambient light sensor with a test lamp that is connected to a good ground.
Does the test lamp illuminate?		 - Go to Step 4  Go to Step 5 
4
  1. Connect a fused jumper wire between the signal circuit of the ambient light sensor and the low reference circuit of the ambient light sensor.
  2. With a scan tool, observe the PHOTOCELL VOLTAGE data parameter in the LAMP STATUS data list.
Does the scan tool indicate that the PHOTOCELL VOLTAGE parameter is within the specified range?		 4.5-5.0 V Go to Step 7  Go to Step 6 
5 Test the signal circuit of the ambient light sensor for an open, high resistance, or short to ground. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 11  Go to Step 8 
6 Test the low reference circuit of the ambient light sensor for an open, high resistance, or short to ground. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 11  Go to Step 8 
7 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 .
Did you find and correct the condition?		 - Go to Step 11  Go to Step 9 
8 Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 11  Go to Step 10 
9 Replace the ambient light sensor.
Did you complete the replacement?		 - Go to Step 11  -
10 Replace the BCM. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?		 - Go to Step 11  -
11
  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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