Circuit Description
The electronic brake control module (EBCM) supplies voltage to the BASS relay coil side voltage supply circuit when the stop lamps are active. The coil side control circuit of the BASS relay is permanently grounded at G402.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B3903 Stop Lamp Relay Circuit
Conditions for Running the DTC
| • | The EBCM must be powered. |
| • | This test is run continuously. |
Conditions for Setting the DTC
If the BASS relay coil side voltage supply circuit is out of range for more than 30 milliseconds
Action Taken When the DTC Sets
When DTC B3903 is set, the service vehicle soon lamp will illuminate.
Conditions for Clearing the DTC
| • | The current DTC will clear when the fault is no longer present. |
| • | The ignition key must be cycled OFF and ON. |
| • | A history DTC clears after 100 consecutive ignition cycles in which no faults have occurred. |
| • | Clear the DTC with a scan tool. |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Exterior Lights Schematics Connector End View Reference: Master Electrical Component List | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Is the DTC retrieved as a current DTC? | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections |
3 | Test the relay coil side voltage supply circuit of the BASS relay for a short to voltage, short to ground or an open. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs . Did you find and correct the condition? | Go to Step 6 | Go to Step 4 |
4 | Inspect for poor connections at the harness connector of the electronic brake control module (EBCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 6 | Go to Step 5 |
5 | Replace the EBCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 6 | -- |
6 |
Does the DTC reset? | Go to Step 2 | System OK |
