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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Automatic Transmission Diagnosis - 4L60-E >> Diagnostic Tests >> DTC P0719: Brake Switch Circuit - Low Input >> Diagnostic Procedure

Diagnostic Procedure

  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. Connect scan tool to DLC. Turn ignition on, engine off. Using scan tool, record freeze frame and failure records for reference, and then clear DTCs. Using scan tool, monitor brake switch parameter. Disconnect brake switch harness connector. Using test light connected to ground, probe brake switch ignition feed circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step  4.
  3. Connect fused jumper wire between brake switch ignition feed and input circuits at brake switch harness connector. If status on scan tool changes from OPEN to CLOSED, go to step  7. If scan tool status does not change, go to step  9.
  4. Inspect brake switch circuit fuse. If fuse is open, go to next step. If fuse is okay, go to step  8.
    5. NOTE: Condition affecting brake switch circuit may be caused by a fault in other circuits spliced to brake switch circuit.
  5. Check brake switch ignition feed circuit for short to ground. Repair as necessary. After repairs, go to step  11. If circuit is okay, go to next step.
  6. Check brake switch input circuit for short to ground. Repair as necessary. After repairs, go to step  11. If circuit is okay, go to step  10.
  7. Replace brake switch. See appropriate SHIFT INTERLOCK SYSTEMS article. After repairs, go to step  11.
    8. NOTE: Condition affecting brake switch circuit may be caused by a fault in other circuits spliced to brake switch circuit.
  8. Check for open in brake switch ignition feed circuit. Repair as necessary. After repairs, go to step  11.
  9. Check for open in brake switch input circuit. Repair as necessary. After repairs, go to step  11. If circuit is okay, go to next step.
  10. Replace PCM. After replacement, program PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. After repairs, go to next step.
  11. Using scan tool, clear DTCs. Turn ignition on, engine off. Apply and release brake pedal. Ensure TCC brake switch signal indicates 12 volts for 2 seconds. Check for DTCs. If DTC P0719 does not return, system is okay. If DTC P0719 returns, repeat step  1.
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