Circuit Description
The stoplamp switch is closed when the brake is released. When the brake is released, ignition voltage is supplied through the stoplamp switch to the EBCM. When the brake is applied, the switch is open and the signal to the EBCM is low.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The ABS bulb check is complete. |
| • | The vehicle experiences an ABS event involving all 3 brake circuits after the above criteria are met. |
OR:
| • | The ignition is ON. |
| • | The vehicle is moving at a speed of less than 56 km/h (35 mph) when the EBCM completes the bulb check. |
| • | The vehicle reaches a speed of greater than 56 km/h (35 mph) after the above criteria are met. |
Conditions for Setting the DTC
Either of the following conditions will set DTC C0281:
| • | The EBCM detects that the brake is released during an ABS event involving all 3 brake circuits. |
| • | The EBCM detects that the brake is applied for the entire time that the ignition is ON. |
Conditions for Clearing the DTC
| • | Repair the condition(s) responsible for setting the DTC. |
| • | Use a scan tool in order to clear the DTC. |
Diagnostic Aids
Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Inspect for the following:
| • | Backed out terminals |
| • | Improper mating |
| • | Broken locks |
| • | Corrosion |
| • | Improperly formed or damaged terminals |
| • | Poor terminal-to-wiring connections |
| • | Physically damaged wiring |
| • | Wiring broken inside the insulation |
Test Description
The numbers below refer to the step numbers on the diagnostic table:
-
This step tests for a shorted stoplamp switch.
-
This step tests for an open stoplamp switch.
-
If the system is functioning properly, the scan tool displays On when the brake is applied and Off when the brake is released.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics | ||||
1 | Did you perform the ABS Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check |
2 | Use a scan tool in order to to observe the Brake Switch Status. Does the scan tool display Off? | -- | Go to Step 3 | Go to Step 5 |
3 |
Does the scan tool display On? | -- | Go to Diagnostic Aids | Go to Step 4 |
Does the scan tool display On? | -- | Go to Step 9 | Go to Step 7 | |
Does the scan tool display Off? | -- | Go to Step 9 | Go to Step 6 | |
6 | Test the ignition 3 voltage circuit and the TCC brake switch signal circuit for an open or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 8 |
7 | Test the TCC brake switch signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 8 |
8 | Inspect for poor connections at the harness connector of the 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 12 | Go to Step 10 |
9 | Inspect for poor connections at the harness connector of the stoplamp switch. 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 12 | Go to Step 11 |
10 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Important: Perform the Tire Size Calibration procedure. Refer to Scan Tool Diagnostics Did you complete the replacement? | -- | Go to Step 12 | -- |
11 | Replace the stoplamp switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes. Did you complete the replacement? | -- | Go to Step 12 | -- |
Does the system function normally? | -- | System OK | Go to Step 2 | |
