Canyon 4WD L5-3.5L VIN 6 (2004)
Body Control Module: Description and Operation
BODY CONTROL MODULE (BCM)
The body control module (BCM) monitors several inputs in order to arm and disarm the CTD system. The BCM controls the alarm function outputs.
When the BCM detects an unauthorized entry, any door opened, the BCM applies ground to the horn, the park lamp and the headlamp relays. The BCM
will send messages to the security telltale in the instrument cluster through the Class 2 serial data link. The BCM has the following 8 basic modes for
operating the CTD system. The more detailed descriptions are below.
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Off state
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Idle state
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Disarmed state
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Ready-to-arm state
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Arm initiated state
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Arm delay state
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Armed state
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Alarm state
The BCM has the following 6 discrete inputs in order to monitor the CTD system:
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Ignition 1
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Driver door latch, door jamb switch
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Passenger door latch, door jamb switch
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Door lock relay
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Door key switch
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Passenger door unlock relay
The BCM applies ground once per second for approximately 2 minutes, or until a valid input to disarm the system is received by the BCM.
The body control module (BCM) contains the logic of the theft deterrent system. The BCM provides the 5-volt reference to operate the Passlock sensor.
The BCM also measures the voltage of the off/run/crank voltage. The voltage measured will indicate whether the Passlock sensor has been activated and
whether the resistance value from the sensor is a valid value or the tamper value. If voltage measured is in the valid range, the BCM compares this
voltage to a previously learned voltage code. If the voltage codes match, the BCM sends a serial data message containing a password to the engine
control module (ECM). If the voltage codes do not match, or the voltage is in the tamper range, or there is a circuit fault, the BCM will not send the
correct password to the ECM, and the vehicle will not start.
