Diagnostic Procedure
WARNING: This page is about a different car, the 2003 Buick Regal and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
- Did you perform the diagnostic system check? If so, go to next step. If not, see DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM.
- Install a scan tool. Turn ignition ON, engine OFF. Before clearing the DTCs, use the scan tool to record the failure records for reference. Using the Clear Info function will erase the stored failure records from the PCM. Record the failure records. Clear the DTCs. With a scan tool, observe the TCC brake switch parameter. Apply the brake pedal. Does the scan tool display OPEN? If so, see DIAGNOSTIC AIDS . If not, go to next step.
- Turn ignition OFF. Disconnect the TCC brake switch 4-pin connector. Turn ignition ON, engine OFF. With a scan tool, observe the TCC brake switch parameter. Does the scan tool display OPEN? If so, go to step 5 . If not, go to next step.
- Test the signal circuit (CKT 420) of the TCC brake switch for a short to power between the PCM and the TCC brake switch. Did you find and correct the condition? If so, go to step 7 . If not, go to step 6 .
- Replace the TCC brake switch (stoplamp switch). See STOPLAMP SWITCH under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to step 7 .
- Replace the PCM. See POWERTRAIN CONTROL MODULE under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to next step.
- Perform the following procedure to verify the repair:
- Select DTC.
- Select Clear Info.
- Turn ignition ON, engine OFF.
- Apply the brake pedal. The TCC brake switch must be open for more than 2 seconds.
- Select SPECIFIC DTC.
- Enter DTC P0724.
Has the test run and passed? If so, go to next step. If not, go to step 2 .
- With a scan tool, observe the stored information, capture info and DTC info. If there are any DTCs that are displayed by the scan tool and have not been diagnosed, go to the appropriate SELF-DIAGNOSTICS article under ENGINE PERFORMANCE. If there are no more codes, the system is OK.