Circuit Description
The brake switch reports brake pedal status to the powertrain control module (PCM). The brake switch indicates that the brake pedal is either applied or released. This normally-closed switch supplies battery voltage on circuit 420 to the PCM. Applying the brake pedal opens the brake switch, interrupting voltage to the PCM. When the PCM receives 0 volts at the brake switch input, and the torque converter clutch (TCC) is engaged, the PCM turns OFF the TCC solenoid valve.
When the PCM detects battery voltage on circuit 420 indicating a closed brake switch (pedal released) during a number of decelerations, then DTC P0724 sets. DTC P0724 is a type D DTC.
Conditions for Running the DTC
| • | No VSS DTCs P0502 or P0503. |
| • | The vehicle speed is greater than 32 km/h (20 mph) for more than 6 seconds. |
| • | The vehicle speed decreases to 8 km/h (5 mph) and takes more than 4 seconds. |
| • | The vehicle speed is less than 8 km/h (5 mph). |
| • | The above conditions must occur 7 times. |
Conditions for Setting the DTC
DTC P0724 sets if the brake switch is closed (voltage to PCM) without opening for 2 seconds while the conditions for running the DTC are met.
Action Taken When the DTC Sets
The PCM does not illuminate the malfunction indicator lamp (MIL).
Conditions for Clearing the DTC
| • | A scan tool clears the DTC from PCM history. |
| • | The PCM clears the DTC from the 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 is OFF long enough in order to power down the PCM. |
Diagnostic Aids
| • | Ensure that the brake switch is properly adjusted. |
| • | 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 number below refers to the step numbers on the diagnostic table.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||
Important: Before clearing the DTCs, use the scan tool in order to record the Failure Records. Using the Clear Info function erases the Failure Records. Did the brake switch status change from Closed to Open? | -- | |||||||
3 | Replace the brake switch. Refer to Stoplamp Switch Replacement. Is the replacement complete? | -- | -- | |||||
4 | Inspect circuit 420 for a short to power. Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | ||||||
5 | Inspect circuits 420 and 1339 for a short together. Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | ||||||
6 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Is the replacement complete? | -- | -- | |||||
7 | Repair the wiring as needed. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |||||
8 | Perform the following in order to verify the repair:
Has the test run and passed? | -- | System OK |
