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Diagnostic Procedure

WARNING: This page is about a different car, the 2002 GMC Yukon XL, 2002 GMC Sierra, 2002 Chevrolet Suburban, and 2002 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the diagnostic system check? If so, go to next step. If not, see DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  2. Install a scan tool. Turn ignition on, engine off. Before clearing the DTCs, use the scan tool to record the failure records. Using the CLEAR INFO function erases the failure records from the PCM. Record the failure records. Clear the DTCs. Select the TCC BRAKE SWITCH on the scan tool. Do not apply the brake pedal. Does the stoplamp switch indicate CLOSED when the brake pedal is not applied? If so, see DIAGNOSTIC AIDS . If not, go to next step.
  3. Remove the brake fuse. Inspect the brake fuse for an open. Is the fuse open? If so, go to step  10. If not, go to next step.
  4. Turn ignition off. Disconnect the PCM connector C1 from the PCM. Connect a 12-volt test light to a good ground. Using the Connector Test Adapter Kit (J-35616-A) and the 12-volt test light, probe PCM harness connector C1 terminal No. 33. Reinstall the fuse. Turn ignition on, engine off. Do not apply the brake pedal. Does the test light illuminate? If so, go to step  15. If not, go to next step.
  5. Turn ignition off. Remove the harness connector from the stoplamp switch. Use a DVOM to measure voltage at terminal "D" of the stoplamp switch harness connector. Turn ignition on, engine off. Does the voltage measure 10-13 volts? If so, go to step  7. If not, go to next step.
    6. NOTE: The condition that affects this circuit may exist in other connecting branches of the circuit.
  6. Test the ignition 3 voltage circuit (441) for an open. Did you find and correct the condition? If so, go to step  16.
  7. Turn ignition on, engine off. Install a fused jumper wire from terminal "C" to terminal "D" of the stoplamp switch harness connector. Probe the PCM harness connector C1 terminal No. 33 with the test light. Does the test light illuminate? If so, go to step  9. If not, go to next step.
    8. NOTE: The condition that affects this circuit may exist in other connecting branches of the circuit.
  8. Test the brake switch signal circuit (420) for an open. Did you find and correct the condition? If so, go to step  16.
  9. Replace the stoplamp switch. See STOPLAMP SWITCH  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to step  16.
  10. Turn ignition on, engine off. Apply and hold the brake pedal. Install a new fuse while keeping the brake pedal applied. Does the fuse open with the brake pedal applied? If so, go to next step. If not, go to step  12.
    11. NOTE: The condition that affects this circuit may exist in other connecting branches of the circuit.
  11. Test the ignition 3 voltage circuit (441) for a short to ground. Did you find and correct the condition? If so, go to step  16.
  12. With ignition on, release the brake pedal. Does the fuse open when the brake pedal is released? If so, go to next step. If not, see DIAGNOSTIC AIDS .
  13. Disconnect the PCM connector C1 from the PCM. Additional DTCs may set. Turn ignition on, engine off. Install a new fuse. Do not apply the brake pedal. Does the fuse open? If so, go to next step. If not, go to step  15.
    14. NOTE: The condition that affects this circuit may exist in other connecting branches of the circuit.
  14. Test the brake switch signal circuit (420) for a short to ground. Did you find and correct the condition? If so, go to step  16.
  15. Replace the PCM. See POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to next step.
  16. Perform the following procedure to verify the repair:
    • Select DTC.
    • Select CLEAR INFO.
    • Turn ignition on, engine off.
    • The brake pedal is not applied.
    • Select TCC BRAKE SWITCH on the scan tool.

    Does the stoplamp switch indicate CLOSED when the brake pedal is not applied, then indicate OPEN when the brake pedal is applied? If so, system is okay. If not, go to step  1.

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