Diagnostic Procedure

WARNING: This page is about a different car, the 2003 Cadillac Seville and 2003 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.

Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM.

NOTE: 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.

Install a scan tool. Turn ignition on, with engine off. Record the Failure Records. Clear the DTCs. Select TCC Brake Switch on the scan tool. Disconnect the TCC brake switch connector. Does the TCC brake switch status change from CLOSED to OPEN? If yes, go to step 4. If no, go to next step.
Test the TCC brake switch signal circuit (CKT 420) for a short to voltage. Did you find and correct the condition? If yes, go to step 6. If no, go to step 5.
Replace the TCC brake switch. See appropriate STOP LAMP SWITCH in BRAKES article. Did you complete the replacement? If yes, go to step 6.
Replace PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - DEVILLE & SEVILLE article. Did you complete the replacement? If yes, go to next step.
Perform the following procedure in order to verify the repair:
- Select DTC.
- Select Clear Info.
- Turn ignition on, with 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 yes, go to next step. If no, go to step 2.
Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.