"C", "G", "K", "L", "M", "S" & "T" Series

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.
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 Body Control Module (BCM) horn output ON and OFF. If horns are on at all times, go to next step. If horns are not on at all times, check for an intermittent problem.
Turn ignition to OFF position. Remove horn relay. If horns are on at all times, go to step 8. If horns are not on at all times, go to next step.
Connect test light between battery voltage circuit of horn relay coil and horn relay control circuit (Black wire). If test light illuminates, go to next step. If test light does not illuminate, go to step 6.
Test horn relay control circuit (Black wire) for short to ground. Horn relay control circuit includes horn switch. If problem was found, repair as necessary. After repair, go to step 11. If problem was not found, go to step 7.
Inspect for poor connections at horn relay. If problem was found, repair as necessary. After repair, go to step 11. If problem was not found, go to step 9.
Inspect for poor connections at BCM. If problem was found, repair as necessary. After repair, go to step 11. If problem was not found, go to step 10.
Repair short to voltage in horn control circuit (Black wire). After completing repair, go to step 11.
Replace horn relay. After repair, go to step 11.
Replace BCM. See appropriate BODY CONTROL MODULES article. After repair, go to next step.
Operate horn to verify repair. If horns do not operate correctly, repeat test beginning at step 2.