Circuit Description
The electronic brake control module (EBCM) monitors brake pedal position through the stop lamp switch. The stop lamp switch is closed when the brake pedal is pressed and the stop lamp switch opens when the brake pedal is released. When the stop lamp switch is closed, the EBCM receives a voltage signal from the stop lamp switch. The stop lamp switch receives power from the STOP fuse.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C1249 Stop Lamp Switch Circuit Open
Conditions for Running the DTC
DTC C1249 can be set anytime.
Conditions for Setting the DTC
The EBCM detects an open in the stop lamp switch circuit.
Action Taken When the DTC Sets
| • | The EBCM turns ON the Antilock Brake System (ABS) indicator. |
| • | The EBCM turns ON the vehicle stability control (VSC) indicator, if equipped. |
Conditions for Clearing the DTC
The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.
Diagnostic Aids
Thoroughly inspect the wiring and the connectors. An incomplete inspection of the wiring and the connectors may result in a misdiagnosis, causing a part replacement with the reappearance of the malfunction.
The following are possible causes of the malfunction:
| • | An open STOP fuse, possible short to ground in its circuitry |
| • | A misadjusted stop lamp switch |
| • | A faulty stop lamp switch |
| • | A open or high resistance in the brake switch input circuit |
| • | A short to voltage in the brake switch input circuit |
| • | An internal EBCM malfunction |
If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections .
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics Connector End View Reference: Antilock Brake System Connector End Views | ||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||
Press and release the brake pedal while observing the stop lamps. Do the stop lamps come ON and go OFF? | -- | Go to Step 3 | ||||||||
3 |
Is the voltage within the specified range? | 8-14 V | Go to Step 4 | Go to Step 6 | ||||||
4 | Measure the voltage between the stop lamp circuit of the EBCM and a good ground with the brake pedal released. Is the voltage as specified? | Below 1 V | Go to Step 5 | Go to Step 7 | ||||||
5 | Test the EBCM ground circuits for an open or high resistance. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 8 | ||||||
6 | Locate and repair the following in the stop lamp circuit of the EBCM.
Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 9 | -- | ||||||
7 | Locate and repair the short to voltage in the stop lamp circuit of the EBCM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 9 | -- | ||||||
8 | Replace the brake pressure modulator valve (BPMV). Refer to Brake Pressure Modulator Valve Assembly Replacement . Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||
9 |
Does the DTC reset? | -- | Go to Step 2 | System OK | ||||||
