Test Description

WARNING: This page is about a different car, the 2005 GMC Canyon and 2005 Chevrolet Colorado. 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.

3: This step tests for voltage at the voltage supply side of the low beam headlamp relay.
4: This step verifies that the BCM is providing ground to the low beam headlamp relay.
5: This step tests if ground is constantly being applied to the low beam headlamp relay.
6: This step tests if there is opposing voltage present or an open low beam headlamp relay control circuit.
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 Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems
1	Did you perform the Diagnostic System Check - Vehicle?	Go to Step 2	Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2	Install a scan tool. Turn ON the ignition, with the engine OFF. With a scan tool, command the low beams ON and OFF. Does the low beam headlamp relay turn ON and OFF with each command?	Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems	Go to Step 3
3	Turn OFF the ignition. Disconnect the low beam headlamp relay. Turn ON the ignition, with the engine OFF. Probe the battery positive voltage circuit of the low beam headlamp relay 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	Connect a test lamp between the control circuit of the low beam headlamp relay and the battery positive voltage circuit of the low beam headlamp relay. With a scan tool, command the low beam headlamp relay 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 relay for a short to voltage or an open. Refer to Circuit Testing andWiring 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 relay 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 relay. 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 body control module (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 relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair?	Go to Step 13	-
11	Replace the low beam headlamp relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems. Did you complete the replacement?	Go to Step 13	-
12	Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement?	Go to Step 13	-
13	Use the scan tool in order to clear the DTCs. 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