Circuit Description
The TCC/Stoplamp Switch indicates the brake pedal status. The normally closed brake switch supplies a B+ signal on circuit 420 to the Vehicle Control Module (VCM). The signal voltage circuit opens when the brakes are applied.
If the VCM detects a closed TCC/Stoplamp switch during decelerations, then DTC P0724 sets. DTC P0724 is a type D DTC.
Conditions for Setting the DTC
| • | No OSS DTC P0502. |
| • | The VCM detects a closed TCC/Stoplamp Switch/circuit (12 volts) for 2 seconds during decelerations. |
| • | The following sequence of events occurs 10 consecutive times: |
| 1. | The vehicle speed is greater than 32 km/h (20 mph) for 6 seconds. |
| 2. | Then the vehicle speed is 8-32 km/h (5-20 mph) for 4 seconds. |
| 3. | Then the vehicle speed is less than 8 km/h (5 mph). |
Action Taken When the DTC Sets
| • | The VCM does not illuminate the Malfunction Indicator Lamp (MIL). |
| • | DTC P0724 is stored in VCM history. |
Conditions for Clearing the DTC
| • | A scan tool can clear the DTC from the VCM history. The VCM clears the DTC from the VCM history if the vehicle completes 40 warm-up cycles without a failure reported. |
| • | The VCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the VCM. |
Diagnostic Aids
| • | Inspect the wiring at the VCM, the TCC/Stoplamp Switch connector and all other circuit connecting points 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 |
| - | Moisture intrusion |
| - | Corrosion |
| • | When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change. |
| • | Ask about the customer's driving habits and any unusual driving conditions he or she might have, such as stop and go traffic or expressway driving. |
| • | Inspect the brake switch for proper mounting and adjustment. |
| • | Inspect for the most current calibration ID and the latest bulletins. |
| • | First diagnose and clear any engine DTCs or TP Sensor codes that are present. Then inspect for any transmission DTCs that may have reset. |
Test Description
The numbers below refer 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? | -- | ||
2 |
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 stored Failure Records from the VCM. Did the TCC/Brake Switch status change from Closed to Open? | -- | ||
Did the TCC/Brake Switch status change from Closed to Open? | -- | |||
4 | Replace the Stoplamp Switch. Refer to Stoplamp Switch Replacement. Is the replacement complete? | -- | -- | |
5 | Inspect circuit 420 for a short to B+. Refer to General Electrical Diagnosis in Wiring Systems. Did you find a short to B+ condition? | -- | ||
6 | Replace the VCM. Refer to VCM Replacement/Programming. Is the replacement complete? | -- | -- | |
7 | In order to verify your repair, perform the following procedure:
Does the Scan Tool TCC Brake Switch status change from Closed to Open? | -- | System OK |
