C0281

Part 1 Of 2:

Part 2 Of 2:

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 it is not detected when the EBCM expects it, DTC C0281 will set.

CONDITIONS FOR SETTING 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 DTC SETS
- The ABS is not disabled
- The ABS indicator lamp will not light.

DTC C0281 is an Information only DTC. The DTC is stored in memory, but the ABS indicator lamp will not light and ABS will not be disabled.

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 CKT 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 data list display to monitor the brake switch status.
4. This step will try to simulate an open stoplamp switch by removing the stoplamp switch harness connector.
5. This step decides between a short to voltage in CKT 420 and a malfunctioning EBCM.
6. This step eliminates an open in CKT 420 as a possible cause.
7. Damage or corrosion to the EBCM 16-way harness connector terminals could be the cause for an intermittent DTC to set.