Trouble Shooting

System operation may be verified by entering self-test mode. Use DRB to select self-test mode. See VEHICLE COMMUNICATIONS in the appropriate article:
- TESTS W/CODES - BODY CONTROL COMPUTER - 1993 Except New Yorker
- TESTS W/CODES - BODY CONTROL COMPUTER - 1993 New Yorker
- TESTS W/CODES - BODY CONTROL COMPUTER - 1994
  NOTE: Vehicle Theft Security System (VTSS) or VTSS self-test will be inoperative if Powertrain Control Module (PCM) has been replaced within last 20 ignition switch cycles.
On all bodies, once in self-test mode, parking lamps and tail lamps will flash and horn will sound twice. Parking lamps and tail lamps flashing verify their operation, and horn sounding twice verifies proper trunk cylinder position.
Turn ignition switch to OFF position to stop lamps from flashing while keeping system in self-test. While in self-test mode, a horn pulse should occur at each of following steps indicating proper operation:
- Ensure all doors are closed. Open, then close each door. Horn will sound when door ajar switch closes, and then again when switch opens. There must be a one second delay between closing and opening switch.
- Open, then close hood. Horn will sound when hood is opened, and again when it is closed.
- Activate power door locks in both LOCK and UNLOCK directions. Horn will sound after each activation.
- Rotate key in both door lock cylinders to unlock position. Horn will sound as switch closes, and again when it opens. Ensure there is a one second delay between changing switch states, or horn will not sound.
- Press LOCK button. Horn will sound.
- Press UNLOCK button. Horn will sound.
- Cycle ignition switch to RUN position. A single horn pulse will indicate proper operation of ignition input and take VTSS module out of self-test mode.
- For any of these tests, if switch does not remain open or closed for at least one second, the horn will only sound once.
Lack of a horn pulse during any operation, indicates a switch failure. Check for continuity at switch. If switch continuity is okay, check for an open or shorted wire between switch and VTSS module.
Whenever a VTSS malfunction occurs, verify wiring harness is properly connected to all connectors before starting normal diagnosis and repair procedures.