Circuit Description
The electronic brake control module (EBCM) sources 5 volts on the stop lamp switch signal circuit when the stop lamp switch is inactive. The voltage is supplied a ground path through the stop lamp bulbs.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C1295 Brake Lamp Switch Circuit Open
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The stop lamp switch input voltage is between 1.73 volts and 4.88 volts for 2 seconds.
Action Taken When the DTC Sets
| • | The ABS remains functional, but may be less than optimal. |
| • | The ABS indicator remains OFF. |
| • | The TCS operation may be unpredictable. |
Conditions for Clearing the DTC
| • | The condition for the DTC is no longer present and the DTC is cleared with a scan tool. |
| • | The electronic brake control module (EBCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles. |
Diagnostic Aids
Possible causes of this DTC are the following conditions:
| • | A signal circuit of the stop lamp switch is open. |
| • | The stop lamp switch is misadjusted. |
| • | Verify proper stop lamp switch operation using the data list of the scan tool. As the brake is applied, the data list displays the stop lamp switch ON within 2.54 cm (1 in) of travel. |
| • | All brake lamps are open. |
| • | All brake lamp grounds are open. |
| • | Circuit has a wiring problem, terminal corrosion, or poor connections. |
| • | Loose or corroded EBCM ground or ECM ground. |
| • | An internal EBCM problem. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This DTC detects an open stop lamp switch signal circuit from the stop lamp side of the splice pack to the EBCM.
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The EBCM sources 5 volts on the stop lamp switch signal circuit. This small voltage has a ground path through the stop lamp bulbs. This DTC sets if the path to ground is open.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics Connector End View Reference: Antilock Brake System Connector End Views or Lighting Systems Connector End Views in Lighting 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 |
Does the Brake Switch Status parameter display Applied? | Go to Step 4 | Go to Step 3 |
Test the signal circuit of the stop lamp switch for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 7 | |
Press the brake pedal. Are all of the stop lamps OFF? | Go to Step 5 | Go to Diagnostic Aids | |
5 | Test the feed circuit of the stop lamps for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 6 |
6 | Test the ground circuit of the stop lamps for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Diagnostic Aids |
7 | 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 in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 8 |
8 | Replace the EBCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 9 | -- |
9 |
Does the DTC reset? | Go to Step 2 | System OK |
