Circuit Description
The Stop Lamp Switch is normally closed when the brake pedal is released. With the ignition in the RUN position and the brake pedal released, the EBCM will have ignition voltage present at connector C1 terminal C. When the brakes are applied, the voltage present at terminal C of the EBCM will be zero. The EBCM monitors the status of the brake switch in order to initiate an ABS event, if the right conditions exist. If the brake switch signal is detected at the wrong time, or if it is not detected when the EBCM expects it a DTC C0281 will set.
Conditions for Setting the DTC
| • | After power-up, the microprocessor never sees the brake switch released and the vehicle reaches a speed above 24 km/h (15 mph), or |
| • | The vehicle is in an ABS stop for more than 1 second and the brake switch is not depressed |
Action Taken When the DTC Sets
| • | The ABS indicator lamp will not be illuminated |
| • | The ABS will not be disabled |
DTC C0281 is advisory code only. 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, misadjusted Stop Lamp Switch or damage in CKT 420 or CKT 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:
-
This step checks the functionality of the Stop Lamp Switch circuit using the Scan Tool.
-
This step checks for a short to voltage in the Stop Lamp Switch circuit between the Stoplamp Switch and the EBCM.
-
This step checks the functionality of the Stop Lamp Switch circuit using the Scan Tool.
-
This step checks for an open in the Stop Lamp Switch circuit between the Stoplamp Switch and the EBCM.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the Diagnostic System Check performed? | -- | Go to Diagnostic System Check | |||||||
Does the scan tool indicate that the Stop Lamp Switch is closed (when pedal is not applied)? | -- | |||||||||
Does the scan tool indicate that the Stop Lamp Switch is closed? | -- | |||||||||
Does the scan tool indicate that the Stop Lamp Switch is open constantly (pedal applied)? | -- | |||||||||
Is the voltage within the specified range? | 10-15V | |||||||||
6 |
Does the scan tool indicate that the Stop Lamp Switch is open constantly while applying and releasing the brake pedal. | -- | ||||||||
7 | Malfunction is intermittent.
Is repair compete? | -- | Go to Diagnostic System Check | -- | ||||||
8 |
Is repair complete? | -- | Go to Diagnostic System Check | -- | ||||||
9 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Is the repair complete? | -- | Go to Diagnostic System Check | -- | ||||||
10 | Repair the short to voltage in CKT 420. Is the repair complete? | -- | Go to Diagnostic System Check | -- | ||||||
11 | Check for the following:
Is repair complete? | -- | Go to Diagnostic System Check | -- |
