Circuit Description
When the body control module (BCM) senses a request for headlamp or daytime running lamp (DRL) illumination, the BCM sends a pulse width modulated (PWM) ground signal to the low beam headlamp driver module through the low beam headlamp driver module control circuit. The low beam headlamp driver module will illuminate the headlamps, adjusting the intensity based on the PWM signal received.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B2575 Headlamp Control Circuit
Conditions for Running the DTC
The battery voltage must be between 9-16 volts.
Conditions for Setting the DTC
| • | When the BCM receives a command to illuminate the low beam or DRL headlamps and the low beam headlamp driver module control circuit is open or shorted to voltage. |
| • | When the BCM does not receive a command to illuminate the low beam or DRL headlamps and the low beam headlamp driver module control circuit is shorted to ground. |
Action Taken When the DTC Sets
The low beam and DRL headlamps will not operate or will remain always on.
Conditions for Clearing the MIL/DTC
| • | This DTC will clear on current status after the condition for setting the fault is corrected. |
| • | A history DTC will clear after 100 consecutive ignition cycles without a fault present. |
| • | History and current DTCs can be cleared using a scan tool. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step tests for voltage at the voltage supply side of the low beam headlamp driver module.
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This step verifies that the BCM is providing PWM ground to the low beam headlamp driver module.
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This step tests if ground is constantly being applied to the low beam headlamp driver module.
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This step tests if there is opposing voltage present or an open low beam headlamp driver module control circuit.
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After replacement of the BCM you must calibrate the new module for proper operation.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics Connector End View Reference: Lighting Systems Connector End Views or Data Communication Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Does the low beam headlamp driver module turn ON and OFF with each command? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 |
Does the test lamp illuminate? | Go to Step 4 | Go to Step 10 | |
Does the test lamp turn ON and OFF with each command? | Go to Step 8 | Go to Step 5 | |
Does the test lamp remain illuminated with each command? | Go to Step 7 | Go to Step 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 . 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 . 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 s. 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 . 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 . Did you complete the repair? | Go to Step 13 | -- |
11 | Replace the low beam headlamp driver module. Refer to Relay Replacement . Did you complete the replacement? | Go to Step 13 | -- |
Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 13 | -- | |
13 |
Does the DTC reset? | Go to Step 2 | System OK |
