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Circuit Description

BCM sets a DTC 7 when BCM detects a short to ground or short to voltage in horn relay coil circuit 28 (Black wire) between horn relay and BCM. Horns are activated when ground is applied to horn relay coil through circuit 28 (Black wire) between Body Control Module (BCM), horn switch in steering wheel and underhood junction block connector C2 terminal E7.

  1. Ensure courtesy lights and power door locks are operational. Perform diagnostic system check of Body Control Module (BCM). See BODY CONTROL MODULE DIAGNOSTIC SYSTEM CHECK  under TROUBLE SHOOTING. If BCM DTC 7 is present, go to next step.
  2. Turn ignition switch to LOCK position. Disconnect horn relay. Disconnect BCM connector C2. Turn ignition switch to ON position. Using a test light connected to ground, check for battery voltage at BCM connector C2 terminal D10 (Black wire). See Figure . If test light illuminates, go to step  4 . If test light does not illuminate, go to next step.
  3. Using a test light connected to positive battery, probe BCM connector C2 terminal D10 (Black wire). See Figure . If test light illuminates, go to step  5 . If test light does not illuminate, go to step  6 .
  4. Disable air bag system. See DISABLING & ACTIVATING AIR BAGS in AIR BAG RESTRAINT SYSTEMS article. Repair short to voltage in circuit 28 (Black wire) between underhood junction block connector C2 terminal E7 and BCM harness connector terminal D10, or short to voltage in circuit 28 (Black wire) between underhood junction block connector C2 terminal E7 through steering column to horn switch in steering wheel. See appropriate wiring diagram in STEERING COLUMN SWITCHES - TRUCKS - EXCEPT TRACKER . After repairs, go to step  7 .
  5. Disable air bag system. See DISABLING & ACTIVATING AIR BAGS in AIR BAG RESTRAINT SYSTEMS article. Repair short to ground in circuit 28 (Black wire) between underhood junction block connector C2 terminal E7 and BCM harness connector terminal D10, or short to ground in circuit 28 (Black wire) between underhood junction block connector C2 terminal E7 through steering column to horn switch in steering wheel. See appropriate wiring diagram in STEERING COLUMN SWITCHES - TRUCKS - EXCEPT TRACKER . After repairs, go to step  7 .
  6. Verify which BCM type vehicle is equipped with. See BCM TYPE VERIFICATION  under SELF-DIAGNOSTIC SYSTEM. Replace Body Control Module (BCM). See BODY CONTROL MODULE  under REMOVAL & INSTALLATION. If vehicle is equipped with factory installed Central Theft Deterrent (CTD) anti-theft system, perform CTD relearn procedure. See CENTRAL THEFT DETERRENT (CTD) RELEARN  under PROGRAMMING. Program feature customization settings. See ENTER FEATURE CUSTOMIZATION MODE  under PROGRAMMING.
  7. Clear BCM DTCs. See ON-BOARD DIAGNOSTICS  under SELF-DIAGNOSTIC SYSTEM. Operate vehicle in attempt to reset DTC. If BCM DTCs reset, go to step  2 . If BCM DTCs does not remain, system is okay.
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