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Century & Regal

  1. If horn system diagnostic system check was performed, go to next step. If horn system diagnostic system check was not performed, see HORN SYSTEM DIAGNOSTIC SYSTEM CHECK (CENTURY & REGAL)  under SELF-DIAGNOSTIC SYSTEM.
  2. Connect scan tool to Data Link Connector (DLC). DLC is located below left side of instrument panel, to right of steering column. Turn ignition switch to RUN position. Using scan tool, command horn relay ON and OFF. If horns remain on at all times, go to next step. If horns do not remain on at all times, check for intermittent or poor connections. Repair as necessary.
  3. Turn ignition switch to OFF position. Remove horn relay from underhood fuse block, located on right side of engine compartment, mounted to strut tower. If horns turn off, go to next step. If horns still sound, go to step  8 .
  4. Connect test light between horn relay cavities No. 85 (coil power supply circuit) and horn relay cavity No. 86 (relay control circuit). See Figure . If test light illuminates, go to next step. If test light does not illuminate, go to step  6 .
    5. CAUTION: Horn switch is part of inflatable restraint steering wheel module. Disable air bag system. See SERVICE PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM in appropriate AIR BAG RESTRAINT SYSTEMS article.
  5. Check for short to ground in horn relay control circuit (Black wire) between horn switch, horn slip ring and horn relay. Check for short to ground in horn relay control circuit (Black wire) between BCM harness connector C3 terminal A5 and horn relay socket terminal No. 86. See Figure and Figure . If circuit is okay, go to step  7 . If circuit is not okay, repair as necessary. After repair, go to step  11 .
  6. Check horn relay connections for intermittent or poor terminal contact. If terminal contact is okay, go to step  9 . If terminal contact is not okay, repair as necessary. After repair, go to step  11 .
  7. Check BCM connector C3 for intermittent or poor terminal contact. If terminal contact is okay, go to step  10 . If terminal contact is not okay, repair as necessary. After repair, go to step  11 .
  8. Repair short to voltage in horn control circuit (Black wire). After repair, go to step  11 .
  9. Replace horn relay. After repair, go to step  11 .
  10. Replace BCM. Program as necessary. See BODY CONTROL MODULES - CENTURY & REGAL article. After repair, go to next step.
  11. Operate horn system. If horns operate properly, system is okay at this time. If horns do not operate properly, go to step  1 .
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