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Diagnostic Aids

WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
DTC B2648

Step Action Value(s) Yes No
Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics 
Connector End View Reference: Master Electrical Component List in Wiring Systems.
1 Did you perform the 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. With a scan tool, observe the ambient light sensor parameter in the body control module data list.
Does the scan tool indicate that the ambient light sensor parameter is within the specified range?		 1.5-6.0 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 ambient light sensor parameter.
Does the scan tool indicate that the ambient light sensor parameter is greater than the specified value?		 6.0 V Go to Step 4  Go to Step 5 
4
  1. Turn OFF the ignition.
  2. Connect a 3 amp fused jumper wire between the signal circuit of the ambient light sensor and the low reference circuit of the ambient light sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Ambient Light Sensor parameter.
Does the scan tool indicate that the Ambient Light Sensor parameter is less than the specified value?		 1.50 V Go to Step 8  Go to Step 6 
5 Test the signal circuit of the ambient light sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 12  Go to Step 9 
6 Test the signal circuit of the ambient light sensor for 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 12  Go to Step 7 
7 Test the low reference circuit of the ambient light sensor for a high resistance, a short to voltage, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 12  Go to Step 9 
8 Inspect for a high resistance 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 12  Go to Step 10 
9 Inspect for a high resistance at the harness connector of the body control module (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 12  Go to Step 11 
10 Replace the ambient light sensor. Refer to Daytime Running Lamps (DRL) Ambient Light Sensor Replacement .
Did you complete the replacement?		 - Go to Step 12  -
11
IMPORTANT: Perform the set up procedure for the body control module (BCM). Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control Systems.
Replace the BCM. Refer to Body Control Module Replacement in Body Control System.Did you complete the replacement?		 - Go to Step 12  -
12
  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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