Circuit Description
The TCC brake switch reports brake pedal status to the PCM. The TCC brake switch indicates that the brake pedal is either applied or released. The normally-closed switch supplies battery voltage to the PCM. Applying the brake pedal opens the TCC brake switch, interrupting voltage to the PCM. When the PCM receives 0 volts at the TCC brake switch input, the PCM turns OFF the torque converter clutch pulse width modulation (TCC PWM) solenoid valve.
If the PCM detects a closed TCC brake switch (indicating pedal released) during deceleration, then DTC P0724 sets. DTC P0724 is a type D DTC.
Conditions for Running the DTC
No VSS DTCs P0502 or P0503.
Conditions for Setting the DTC
The TCC brake switch indicates continuously CLOSED (12 volts) while the following conditions occur 7 times:
| • | The vehicle speed is greater than 32 km/h (20 mph) for 6 seconds; |
| • | Then the vehicle speed decreases to 8 km/h (5 mph) and takes 4 seconds; |
| • | Finally, 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 the PCM history. |
| • | The PCM clears the DTC from the PCM history if the vehicle completes 40 consecutive warm-up cycles without a 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
| • | Inspect the wiring at the PCM, the TCC 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, 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.
-
A Scan Tool display that changes from Closed to Open when the TCC brake switch is disconnected indicates a faulty TCC brake switch.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls | |||||||
Important: Before clearing the DTCs, use the Scan Tool in order to record the Failure Records for reference. Using the Clear Info function will erase the stored Failure Records from the PCM. Did the TCC brake switch status change from Closed to Open? | -- | |||||||||
3 | Inspect circuit 420 (PPL) for a short to power. Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | ||||||||
4 | Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |||||||
5 | Replace the TCC brake switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes. Is the replacement complete? | -- | -- | |||||||
6 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Is the replacement complete? | -- | -- | |||||||
7 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | System OK |
