C0281

Circuit Description
The stoplamp switch is normally closed when the brake pedal is released. With the ignition in the RUN position and the brake pedal released, ignition voltage is supplied to terminal B5 of the EBCM. When the brakes are applied, the voltage will drop to zero at terminal B5. The EBCM monitors the status of the brake switch. If the brake switch signal is detected at the wrong time, or if it is not detected when the EBCM expects it, DTC C0281 will set.

Conditions for Running the DTC
- Ignition switch in the RUN position.
- The ABS bulb check is completed

Conditions for Setting the DTC
- After power up, the EBCM never detects that the brake switch has been released before the vehicle reaches 56 km/h (35 mph).
- The vehicle is in an ABS stop involving all three hydraulic channels for more than 1 second without the EBCM detecting that the brake switch has been applied.

Action Taken When the DTC Sets
- The ABS is not disabled.
- The ABS indicator lamp will not light.

DTC C0281is an ABS and DRP Information Only DTC. The DTC is stored in memory, the ABS indicator lamp will not light, and the ABS or the DRP will not be disabled.
For a detailed explanation of DTC malfunction responses, refer to Self-Diagnostics

Conditions for Clearing the DTC
- Repair the conditions responsible for setting the DTC
- Use the Scan Tool Clear DTCs function

Diagnostic Aids
DTC C0281 can be set by a faulty stop lamp switch, or damage in CAT 420 or 441.
Thoroughly check any circuitry that is suspected of causing the intermittent complaint for the following conditions:
- Backed out terminals
- Improper mating
- Broken locks
- Improperly formed or damaged terminals
- Poor terminal to wiring connections
- Physical damage to the wiring harness

Test Description
The numbers below refer to the steps in the diagnostic table:
2. Use the scan tool to establish the state of the stoplamp switch input to the EBCM.
3. Use the scan tool to monitor the brake switch status while attempting to change the state using the brake pedal.
4. By disconnecting the stoplamp switch and observing the scan tool, you can further determine the location of the malfunction.