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Home >> Chevrolet >> 2000 >> C3500 HD 6.5 F, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - Diesel >> Diagnostic Tests >> DTC P0571: Cruise Brake Switch Circuit >> Diagnostic Procedures

Diagnostic Procedures

  1. If OBD system check has been performed, go to next step. If OBD system check has not been performed, see ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  2. Connect scan tool. Turn ignition on. Apply brakes. If scan tool displays cruise brake switch closed, and then open when brakes are applied, go to next step. If scan tool does not display cruise brake switch closed, and then open when brakes are applied, go to step  7.
  3. Apply brakes again. If scan tool displays cruise brake switch open, and then closed when brakes are applied, go to step  9. If scan tool does not display cruise brake switch open, and then closed when brakes are applied, go to next step.
  4. Turn ignition off. Disconnect brakelight switch harness connector. Turn ignition on. Using test light connected to ground, probe normally open feed circuit (terminal "B") at brakelight switch harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step  10.
  5. Leave brakelight switch harness connector disconnected. Turn ignition on. Turn headlights on. Using test light connected to ground, probe normally open signal circuit (terminal "A") at brakelight switch harness connector. If test light illuminates, go to step  11. If test light does not illuminate, go to next step.
  6. Leave brakelight switch harness connector disconnected. Connect jumper wire between normally open feed circuit (terminal "A") and normally open signal circuit (terminal "B") of brakelight switch harness connector. If scan tool displays cruise brake switch closed, go to step  17. If scan tool does not display cruise brake switch closed, go to step  12.
  7. Leave brakelight switch harness connector disconnected. Turn ignition on. Using test light connected to ground, probe normally closed feed circuit (terminal "F") at brakelight switch harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step  14.
  8. Leave brakelight switch harness connector disconnected. Connect jumper wire between normally closed feed circuit (terminal "F") and normally closed signal circuit (terminal "E") at brakelight switch harness connector. If scan tool displays cruise brake switch closed, go to step  17. If scan tool does not display cruise brake switch closed, go to step  15.
  9. DTC is intermittent. If no additional DTCs are set, see DIAGNOSTIC AIDS . If any additional DTCs are set, perform appropriate DTC test.
  10. Check for open or short to ground in normally open feed circuit. Repair as necessary. After repairs, go to step  19.
  11. Check for short to voltage in normally open signal circuit. Repair as necessary. After repairs, go to step  19. If circuit is okay, go to step  18.
  12. Check for open or short to ground in normally open signal circuit. Repair as necessary. After repairs, go to step  19. If circuit is okay, go to next step.
  13. Check normally open signal circuit for poor connection at PCM. Repair as necessary. After repairs, go to step  19. If connection is okay, go to step  18.
  14. Check for open or short to ground in normally closed feed circuit. Repair as necessary. After repairs, go to step  19.
  15. Check for open or short to ground in normally closed signal circuit. Repair as necessary. After repairs, go to step  19. If circuit is okay, go to next step.
  16. Check normally closed signal circuit for poor connection at PCM. Repair as necessary. After repairs, go to step  19. If connection is okay, go to step  18.
  17. Replace brakelight switch. After repairs, go to step  19.
  18. Replace PCM. Perform PCM relearn procedures. See PROGRAMMING . After repairs, go to next step.
  19. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, and then enter DTC P0571. Operate vehicle within the conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to step  2.
  20. Using scan tool, check for DTCs. If any undiagnosed DTCs are set, perform appropriate DTC test. If no DTCs are set, system is okay.
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