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Test Description

WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. 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. 3:  Tests for voltage at the voltage supply side of the low beam headlamp driver module.
  2. 4:  Verifies that the body control module (BCM) is providing PWM ground to the low beam headlamp driver module.
  3. 5:  Tests if ground is constantly being applied to the low beam headlamp driver module.
  4. 6:  Tests if there is opposing voltage present or an open low beam headlamp driver module control circuit.
  5. 12:  After replacement of the BCM you must calibrate the new module for proper operation.
DTC B2575

Step Action Yes No
Schematic Reference:  Headlights/Daytime Running Lights (DRL) Schematics  
1 Did you perform the Lighting Systems 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, command the low beams ON and OFF.
Does the low beam headlamp driver module turn ON and OFF with each command?		 Go to TESTING FOR INTERMITTENT CONDITIONS AND POOR CONNECTIONS in Wiring Systems Go to Step 3 
3 
  1. Turn OFF the ignition.
  2. Disconnect the low beam headlamp driver module.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the battery positive voltage circuit of the low beam headlamp driver module with a test lamp that is connected to a good ground.
Does the test lamp illuminate?		 Go to Step 4  Go to Step 10 
4 
  1. Connect a test lamp between the control circuit of the low beam headlamp driver module and the battery positive voltage circuit of the low beam headlamp driver module.
  2. With a scan tool, command the low beam headlamp driver module ON and OFF.
Does the test lamp turn ON and OFF with each command?		 Go to Step 8  Go to Step 5 
5  Does the test lamp remain illuminated with each command? Go to Step 7  Go to Step 6 
6  Test the control circuit of the low beam headlamp driver module for 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 13  Go to Step 9 
7 Test the control circuit of the low beam headlamp driver module 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 13  Go to Step 9 
8 Inspect for poor connections at the low beam headlamp driver module. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Did you find and correct the condition?		 Go to Step 13  Go to Step 11 
9 Inspect for poor connections at the harness connector of the BCM. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Did you find and correct the condition?		 Go to Step 13  Go to Step 12 
10 Repair the battery positive voltage circuit of the low beam headlamp driver module. Refer to WIRING REPAIRS in Wiring Systems.
Did you complete the repair?		 Go to Step 13  -
11 Replace the low beam headlamp control module. Refer to Headlamp Driver Module (HDM) Relay Replacement .
Did you complete the replacement?		 Go to Step 13  -
12 
IMPORTANT: Perform the setup procedure for the BCM.
Replace the body control module (BCM). Refer to BODY CONTROL MODULE REPLACEMENT in Body Control System.Did you complete the replacement?		 Go to Step 13  -
13
  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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