Circuit Description
The brake switch indicates brake pedal status to the Powertrain Control Module (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 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 Setting the DTC
DTC P0719 sets if the PCM detects a closed brake switch or circuit (12 volts) during vehicle deceleration and the following conditions occur seven consecutive times:
| • | The vehicle speed is greater than 32 km/h (20 mph) for 4 seconds; |
| • | then, the vehicle speed is 8-32 km/h (5-20 mph) for 4 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). |
| • | DTC P0724 is stored in the PCM history. |
| • | The PCM inhibits TCC engagement. |
Conditions for Clearing the DTC
| • | A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported. |
| • | 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
| • | Ask about the customer's driving habits. Ask about unusual traffic conditions, stop-and-go driving, etc. |
| • | Inspect the brake switch for proper adjustment. |
| • | Inspect the wiring for poor electrical connections at the PCM. Inspect the wiring for poor electrical connections at the brake switch connector. Look for the following conditions: |
| - | A bent terminal |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Poor terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| • | 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.
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Disconnecting the brake switch connector, and observing a status change, isolates the brake switch as the source of the DTC.
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If the brake switch is properly adjusted, then the brake switch must be replaced.
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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.
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Replace the PCM only after you have completed the preceding diagnostic steps.
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 - 2.3L | |||||
Important: Before clearing the DTCs, use the scan tool in order to record the Failure Records for reference. The Clear Info function will erase the data. Does the brake switch status change from Closed to Open? | -- | |||||||
Replace the brake switch. Refer to Stoplamp Switch, Section 5. Is the replacement complete? | -- | -- | ||||||
Inspect circuit 420 for a short to power. Refer to Troubleshooting Procedures, Section 8. Did you find and correct the condition? | -- | |||||||
Replace the PCM. Refer to Section 6: Powertrain Control Module/EEPROM Replacement/Programming in Engine Controls - 2.3L Is the replacement complete? | -- | -- | ||||||
6 | In order to verify your repair, perform the following procedure:
Has the test run and passed? | -- | System OK | Begin the diagnosis again. Go to Step 1 |
