C 1500 Truck 2WD V8-5.3L VIN T (1999)
sent through the Passlock detecting circuit. This analog voltage signal is of a specific value to the vehicle, and varies from vehicle to vehicle.
When attempting to start the engine, the BCM compares a preset stored analog voltage value with the signal coming from the sensor. Because both
values match, the BCM sends a fuel enable password via the Class 2 serial data link to the Powertrain Control Module (PCM)/vehicle control
module (VCM). As a result, the PCM/VCM allows fuel delivery to the engine.
When attempting to start the engine by means other than using the proper key in the ignition switch, the Passlock sensor sends an analog voltage
signal of a different value. The BCM compares the preset stored analog voltage value with the signal coming from the sensor. Because both values
do not match, the BCM sends a fuel disable password via the Class 2 serial data link to the PCM/VCM. As a result, the PCM/VCM disables the
fuel delivery to the engine.
CONTENT THEFT DETERRENT (CTD)
The body control module (BCM) monitors several inputs in order to arm and disarm the CTD system and 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 applies ground once per second for approximately 2 minutes, or until a valid input to disarm the system is received by the BCM. In
addition the BCM will send messages to security indicator in the instrument cluster via the class 2 serial data link. The BCM has 8 basic modes for
operating the CTD system and 6 discrete inputs to monitor the content theft deterrent system.
The CTD system has a remote panic alarm/vehicle locator feature and can be activated anytime the panic button on the key fob is pressed. When
the panic button is pressed the remote control door lock receiver sends a message to the BCM and will sound the horns and flash the headlamps
and parklamps. The remote panic alarm/vehicle locator state can be disabled by the pressing the panic button on the key fob again, or the system
will time out after 30 seconds.
POWER REQUIREMENTS
The BCM has 3 main voltage feeds CKT 1140, CKT 39, and CKT 41 and 2 ground CKT 1850.
