Theft+Warning+System

toc The stock **theft warning system**, when armed, monitors the doors, hood, locks, and hatch (trunk in convertible, along with radio bezel in convertible), and when any of these are disturbed, sounds the theft warning horn, flashes the headlight high beams, and disables the starter. The 'SECURITY' lamp on the instrument cluster indicates the system state. It can be armed by locking the doors, manually or with the key, but can only be disarmed by unlocking one of the doors or hatch with the key.

The Factory Service Manual has a section on the theft warning system, available here: (93 USDM). Other model years may have different wire colors and harness connections.

=Component locations and descriptions=

Note: 'Pin X' refers to the pin as labeled on the control unit connector, unless otherwise stated. //Function:// Disables starter by interrupting the starter relay coil || || //Function:// Triggers alarm when hood is opened by grounding pin 15.
 * ===A. Theft warning relay=== ||  ||
 * //Location:// Engine bay fuse/relay box
 * ===B. Hood switch=== ||  ||
 * //Location:// Engine bay, in front of driver's side upper shock mount
 * //Location:// Engine bay, in front of driver's side upper shock mount

|| || above the ECU. //Function:// Processes system inputs and triggers outputs. Horn relay is activated when alarm is triggered by grounding pin 12.
 * ===C. Theft warning control unit and horn relay=== ||  ||
 * //Location:// Passenger side footwell, attached to lower dash support,
 * //Location:// Passenger side footwell, attached to lower dash support,

|| || //Function:// Door lock / unlock switch - When key is used to lock the door, pin 7 is grounded. When key is used to unlock the door, pin 11 is grounded. Arms / disarms the system. Door key cylinder tamper switch - If the key cylinder is removed from the door, pin 5 is grounded. || || //Function:// Triggers alarm when door is opened by grounding pin 6.
 * ===D. Door lock switch, unlock switch, key cylinder tamper switch=== ||  ||
 * //Location:// Driver and passenger door handles
 * //Location:// Driver and passenger door handles
 * ===E. Door switch=== ||  ||
 * //Location:// Driver and passenger door jambs
 * //Location:// Driver and passenger door jambs

|| || //Function:// Tells the control unit if the door is unlocked, so it can know if a door was locked or unlocked manually (without a key). || || //Function:// Door switch - Triggers alarm when hatch is opened by grounding pin 6 and 14. Unlock switch - When the hatch is unlocked with a key, pin 10 is grounded. Door key cylinder tamper switch - If the key cylinder is removed from the hatch, pin 5 is grounded. || || //Function:// Horn is sounded when alarm is triggered. || ||
 * ===F. Door unlock sensor=== ||  ||
 * //Location:// Driver and passenger door, inside, below latch
 * //Location:// Driver and passenger door, inside, below latch
 * ===G. Back door switch, unlock switch, key cylinder tamper switch=== ||  ||
 * //Location:// In rear, behind center trim panel (except convertible)
 * //Location:// In rear, behind center trim panel (except convertible)
 * ===H. Theft warning horn=== ||  ||
 * //Location:// Engine bay, underneath battery tray.
 * //Location:// Engine bay, underneath battery tray.

=Normal operation=

To check if the stock alarm is operating correctly, make sure the doors, hood, and hatch are all closed. The SECURITY light on the instrument cluster should not be illuminated. Open each door individually, and confirm the SECURITY light flashes when the door is open and goes out again when the door is closed. Repeat for the hood and hatch. Now, with all doors, hood, and hatch closed, and the driver's window open, lock the driver's door, and confirm the SECURITY light goes solid for 30-40 seconds, then goes out. The system is now armed. Reach inside the open window and unlock and open the driver's door. The alarm should be triggered, sounding the horn and flashing the lights. Get in the car and attempt to start it with the key. The starter should not work. Disarm the alarm by unlocking the driver's door with the key. The horn and lights should stop flashing, and the car should now start with the key.

=Troubleshooting=

The SECURITY light is always flashing
This means the control unit sees one of your doors, hood, or hatch as open. Not only will this prevent the system from arming, but it also places a drain on the battery when the car is parked. A common culprit is the hood switch, as the bracket that holds it in position can be bent downward, causing the hood not to make contact when closed. A fault with the other door switches, hatch switch, key cylinder tamper switches, or harness are also possible. Use Diagnostic Procedure 1 in the FSM extract at the top of the page if the problem is not readily apparent.

The alarm goes off and my key won't disable it
Often this is because the plastic piece connected to the key cylinder in the door breaks off, which means the door unlock switch is never triggered when the door is unlocked with the key, so the control unit never sees the door unlock signal. This can be checked by removing the door panel and looking at the back of the key cylinder. Z1 Motorsports sells a metal replacement which can be seen here. If this is not the problem, use Diagnostic Procedure 7.



=Integration with aftermarket alarm= The stock theft warning system can be retained with an aftermarket alarm, and its wiring harness provides several useful connections to tap into at the control unit. All door switches, key cylinder tamper switches, and lock / unlock sensors act as open circuits when normal (door / hatch / hood closed, key cylinder intact) and connect to ground when activated (door / hatch / hood open, key cylinder removed, door lock / unlock signal). To arm the stock system with the aftermarket alarm, tie the door lock switch, pin 7, to a grounded output when the doors are locked with the remote, and tie the door unlock switch, pin 11, to a grounded output when the doors are unlocked with the remote. If desired, the stock theft warning system can be disabled by simply disconnecting the control unit. This has no effect on any other vehicle systems.

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