C0281

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Part 2 Of 2:

CIRCUIT DESCRIPTION
The Stop Lamp Switch is normally closed. With the ignition in the RUN position and the brake pedal not depressed, the Electronic Brake Control Module (EBCM) will have ignition voltage present at terminal C of the 10-way connector. When the brakes are applied, the ignition voltage present at the EBCM will be zero. In a normal braking situation, if the EBCM senses wheel slippage without seeing the brake switch input, it will set a DTC C0281. The ABS indicator lamp will come on and the code will be stored as an ignition latched DTC.

The EBCM can also sense operating conditions where wheel slippage is occurring without the brakes applied. In this case, the EBCM will attempt to compensate for wheel slippage by initiating an ABS event. When this occurs, the EBCM will sense that there is no brake switch applied. Under these conditions, the EBCM will set a DTC C0281 as an advisory code, which means that the DTC will be stored, however no ABS indicator lamp will light.

CONDITIONS FOR SETTING THE DTC
^ The vehicle is above 15 mph
^ The Stop Lamp Switch never switches during the condition above, or
^ An ABS event initiates without the brake switch is applied.

ACTION TAKEN WHEN THE DTC SETS
^ Depending upon the conditions, DTC C0281 can be either an ignition latched, or advisory code
^ The ABS indicator lamp will not be illuminated if it is set as an advisory code
^ The 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:
2. This step checks the functionality of the Stop Lamp Switch circuit using the Scan Tool.
3. This step checks for a short to voltage in the Stop Lamp Switch circuit between the Stoplamp Switch and the EBCM.
4. This step checks the functionality of the Stop Lamp Switch circuit using the Scan Tool.
5. This step checks for an open in the Stop Lamp Switch circuit between the Stoplamp Switch and the EBCM.