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Home >> Chevrolet >> 2007 >> Chevy Express G3500, Van Passenger Extended >> Repair and Diagnosis >> Body & Frame >> Ignition Switch/Steering Lock >> Immobilizer System >> Description and Operation >> Immobilizer Description and Operation >> Body Control Module
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Body Control Module

The body control module (BCM) contains the theft deterrent system logic. The BCM reads the Passlock™ data from the Passlock™ sensor. If the Passlock™ data is correct, the BCM will pass theft. The BCM will then transmit the fuel continue password to the vehicle control module (VCM)/powertrain control module (PCM).

During the tamper mode, the vehicle may start. The vehicle will then stall. If the BCM receives the wrong Passlock™ data, the vehicle theft deterrent (VTD) will immediately go into the tamper mode. The tamper mode will lock-out the vehicle fuel injectors for 10 minutes. The SECURITY indicator will flash while the VTD is in the tamper mode.

If the Passlock™ sensor sends a correct password to the BCM when the ignition is in the ON position, the BCM will send a fuel enable signal to the VCM/PCM. The VCM/PCM will not disable the fuel due to any BCM message for the remainder of the ignition cycle.