Test G: Horn Does Not Sound
WARNING: This page is about a different car, the 2002 Lincoln Navigator, 2002 Ford Expedition, 2001 Lincoln Navigator, and 2001 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
Horn switch is integral to driver's air bag module on steering wheel.
- Turn ignition switch to LOCK position. Connect New Generation Star (NGS) tester to Data Link Connector (DLC). DLC is located below left side of instrument panel, right of steering column. Using NGS tester, command horn to sound. If horn does not sound, go to next step. If horn sounds, go to step 7.
- Disconnect Central Security Module (CSM) harness connector C256. CSM is located behind left side of instrument panel. Using a fused jumper wire (15-amp), connect between terminals No. 13 (Yellow/Light Green wire) and No. 24 (Yellow/Light Blue wire). If horn does not sound, go to next step. If horn sounds, go to step 5.
- Disconnect horn harness connector C136. Horn is located behind right front headlight. Measure resistance in Yellow/Light Green wire between horn harness connector C136 and CSM harness connector C256. If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, repair open in Yellow/Light Green wire between horn and CSM. See WIRING DIAGRAMS .
- Measure resistance between ground and horn harness connector C136 (Black wire). If resistance is 5 ohms or less, replace horn. If resistance is more than 5 ohms, repair open in Black wire between horn and ground. Ground is located at right front radiator support. See WIRING DIAGRAMS .
- Measure resistance between ground and CSM harness connector C256 terminal No. 10 (Dark Blue wire), while pressing horn switch. Resistance should be 5 ohms or less when pressed and more than 10 k/ohms when released. If resistance is as specified, go to next step. If resistance is not as specified, go to step 7.
- Disconnect all CSM harness connectors. Inspect harness connectors for corrosion and pushed out pins. Connect all CSM harness connectors, ensuring they are connected correctly. Operate system and verify if problem still exists. If problem still exists, replace CSM. See CENTRAL SECURITY MODULE under REMOVAL & INSTALLATION. If problem does not exist, system is operating correctly at this time. Clear DTCs and perform CSM self-test.
- Disconnect CSM harness connector C256. Deactivate air bag system. See AIR BAG SAFETY PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM in appropriate AIR BAG RESTRAINT SYSTEMS article in RESTRAINTS. Disconnect lower clockspring harness connector. Measure resistance in Dark Blue wire between CSM harness connector terminal No. 10 and lower clockspring harness connector. See Fig 1 or Fig 2 . If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, repair open in Dark Blue wire between CSM and clockspring. See WIRING DIAGRAMS .
- Measure resistance between ground and clockspring harness connector (Dark Blue wire). See Fig 1 or Fig 2 . If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, repair short to ground in Dark Blue wire between clockspring and CSM. See WIRING DIAGRAMS .
- Measure resistance in Dark Blue wire between lower clockspring harness connector and upper clockspring harness connector. Measure resistance in Dark Green/Orange wire between lower clockspring harness connector and upper clockspring harness connector. If resistances are 5 ohms or less, replace horn switch. See REMOVAL & INSTALLATION in appropriate AIR BAG RESTRAINTS SYSTEM article in RESTRAINTS. If resistance is more than 5 ohms, replace clockspring. See CLOCKSPRING under REMOVAL & INSTALLATION.