With 4 Speed Automatic
Circuit Description
The brake switch indicates brake pedal status to the PCM. The normally-closed brake switch supplies battery voltage on circuit 420 to the PCM. Applying the brake pedal opens the switch, interrupting voltage to the PCM. Releasing the brake pedal resumes voltage to the PCM. When the PCM senses 0 volts at the brake switch input, the PCM de-energizes the torque converter clutch (TCC) solenoid valve.
When the PCM detects a closed brake switch (stuck OFF) during decelerations, then DTC P0724 sets. DTC P0724 is a type D DTC.
Conditions for Running the DTC
^ The ignition switch is in the RUN position.
^ The system voltage is 8-18 volts.
Conditions for Setting the DTC
DTC P0724 sets if the PCM detects a closed brake switch or circuit (12 volts) during vehicle deceleration and the following conditions occur eight consecutive times:
^ The vehicle speed is greater than 32 km/h (20 mph) for 6 seconds;
^ then, the vehicle speed is 8-32 km/h (5-20 mph) for 3 seconds;
^ then, the vehicle speed is less than 8 km/h (5 mph).
Action Taken When the DTC Sets
^ The PCM does not illuminate the malfunction indicator lamp (MIL).
^ The PCM stores DTC P0724 in PCM history.
Conditions for Clearing the DTC
^ A scan tool clears the DTC from PCM history.
^ The PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without a non-emission-related diagnostic fault occurring.
^ The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.
Diagnostic Aids
^ Ask about the customer's driving habits. Ask about unusual traffic conditions and stop-and-go driving.
^ Inspect the brake switch for proper adjustment.
^ Inspect the wiring at the PCM, the brake switch connector and all other circuit connecting points for the following conditions:
- A backed out terminal.
- A damaged terminal.
- Reduced terminal tension.
- A chafed wire.
- A broken wire inside the insulation.
- Moisture intrusion.
- Corrosion.
^ When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test equipment for a change.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. Disconnecting the brake switch connector, and observing a status change, isolates the brake switch as the source of the DTC.
3. If the brake switch is properly adjusted, then the brake switch must be replaced.
4. This step inspects circuit 420 for a short to power, if the brake switch status on the scan tool did not change in step 2.
5. Replace the PCM only after you have completed the preceding diagnostic steps.