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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 16 (Steering Column & Steering Column Switches) >> Diagnostic Tests >> DTC 7: Horn Circuit Failure >> Diagnostic Procedure

Diagnostic Procedure

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  1. If horns diagnostic system Check was performed, go to next step. If horns diagnostic system check was not performed, perform HORNS DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  2. Depress horn switch. If horns operate properly, go to DIAGNOSTIC AIDS . If horns do not operate properly, go to next step.
  3. Turn ignition switch to OFF position. Remove horn relay. Turn ignition switch to RUN position. Using a test light connected to ground, probe battery voltage circuit of horn relay coil. If test light illuminates, go to next step. If test light does not illuminate, go to step  10.
  4. Connect a test light between horn relay control circuit (Black wire) and battery voltage circuit of horn relay coil. Depress and release horn switch. If test light turns on and then off, go to step  8. If test light does not turn on and then off, go to next step.
  5. It test light remains illuminated when horn switch is released, go to step  7. If test light does not remain illuminated when horn switch is released, go to next step.
    6. NOTE: Horn relay control circuit includes horn slip ring and horn switch.
  6. Disable SIR system. See appropriate AIR BAG RESTRAINT SYSTEM article. Test horn relay control circuit for a short to voltage. If problem was found, repair as necessary. After repair, go to step  13. If problem was not found, go to step  9.
    7. NOTE: Horn relay control circuit includes horn slip ring and horn switch.
  7. Disable SIR system. See appropriate AIR BAG RESTRAINT SYSTEM article. Test horn relay control circuit for a short to ground. If problem was found, repair as necessary. After repair, go to step  13. If problem was not found, go to step  9.
  8. Inspect for poor connections at horn relay. If problem was found, repair as necessary. After repair, go to step  13. If problem was not found, go to step  11.
  9. Inspect for poor connections at harness connector of BCM. If problem was found, repair as necessary. After repair, go to step  13. If problem was not found, go to step  12.
  10. Repair battery voltage circuit of horn relay coil. After repair, go to step  13.
  11. Replace horn relay. After repair, go to step  13.
  12. Replace BCM. See appropriate BODY CONTROL MODULES article. After repair, go to next step.
  13. Clear BCM DTCs. Operate system in order to verify repair. If DTC does not reset, system is okay. If DTC resets, repeat test beginning at step  2.
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