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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1506 (Lighting System) >> Diagnostic Information and Procedures >> DTC B2603 >> Diagnostic Aids

Diagnostic Aids

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.
DTC B2603

Step Action 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, command the DRL relay ON and OFF.
Does the DRL relay turn ON and OFF with each command?
Go to Testing for Intermittent Conditions and Poor Connections Go to Step 3 
3
  1. Disconnect the daytime running lamps (DRL) relay.
  2. Turn ON the ignition, with the engine OFF.
  3. Probe the control circuit of the DRL relay 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. Leave the test lamp connected.
  2. Turn OFF the ignition.
  3. Disconnect the body control module (BCM).
  4. Turn ON the ignition, with the engine OFF.
Does the test lamp illuminate?
Go to Step 5  Go to Step 6 
5 Inspect for poor connections at the DRL relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?
Go to Step 10  Go to Step 8 
6 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 10  Go to Step 9 
7 Repair a short to voltage in the DRL relay control circuit. Refer to Circuit Testing and Wiring Repairs .
Did you complete the repair?
Go to Step 10  -
8 Replace the DRL relay.
Did you complete the replacement?
Go to Step 10  -
9 Replace the BCM. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?
Go to Step 10  -
10
  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 3  System OK