Security System

CIRCUIT CHART
Circuit assignments for the body control module (BCM) relating to security system:

SECURITY SYSTEM
The passlock sensor is powered by circuit 1459. The passlock sensor is grounded by circuit 1835. Passlock sensor data is supplied to the BCM by circuit 1836.

The passlock sensor data supplied to the BCM is in the form of V-codes or voltage codes. When the proper ignition key is turned in the ignition switch, the correct V-code is supplied to the BCM. The BCM responds by sending a serial data password to the engine controller allowing the engine to run.

The security resistor is bypassed under a tamper condition (possible external magnet applied to sensor). In this mode, a specific V-code is supplied to the BCM. The vehicle will not start in this mode.

KEY-IN-IGNITION
When the ignition key is seated in the ignition switch, the key-in-ignition switch contacts close grounding circuit 80. The BCM monitors the state of the key-in-ignition switch, the state of the ignition switch (OFF, ACC or RUN) and the driver's door to control the key-in-ignition chime.

HORN
The BCM controls the operation of the horns for the security system and remote keyless entry (RKE) functions. Circuit 28 is grounded by the BCM when horn operation is desired. Normal operation of the horn is performed by the horn switch grounding the horn relay and is not controlled by the BCM.

There is a 30 second delay prior to setting DTC 2752 - Horn Relay Coil Circuit Low for grounded circuit conditions. It is possible to set DTC 2752 if the horn is operated by the horn switch for greater than 30 seconds