Hombre S Space Cab 2WD V6-4.3L (2000)
Body Control Module: Description and Operation
Body Control System Description
Familiarize yourself with the information and proper diagnosing procedures. The BCM diagnostic system check is an organized approach in order to
identify the cause of a condition that is reported by a BCM system malfunction code.
The BCM diagnostic system check is the starting point for diagnosis of any BCM system complaint. The BCM diagnostic system check will direct you to
the next logical step in diagnosing the complaint. Correct use of the table reduces diagnostic time and prevents unnecessary replacement of good parts.
BCM Functions
The body control module (BCM) is capable of controlling multiple body functions. Components directly connected to the BCM are controlled by the
BCM's outputs. The BCM controls the outputs based on input information that it obtains from the sensors and the switches that are directly connected to
it. The BCM can also borrow information from other vehicle systems connected to the Class 2 serial data link. The BCM evaluates this information and
controls certain body systems by commanding an output ON or OFF.
The BCM is also capable of commanding other vehicle systems to control functions that are not directly wired and/or controlled by the BCM. The BCM
accomplishes this task by sending specific messages on the Class 2 serial data link. The vehicle system capable of performing such function will respond
to the BCM message.
The BCM controls the following functions:
-
Audible Warnings
-
Indicator Warnings
-
Interior Lighting
-
Exterior Lighting.
-
Power Door LOCK/UNLOCK
-
Passlock Theft Deterrent
Audible Warnings
-
key in ignition reminder
-
Fasten seat belt reminder
-
Park brake reminder
-
Turn signal reminder
-
Headlamps ON reminder
Indicator Warnings
-
Security indicator
-
Cargo lamp on indicator
-
Fasten belts indicator
-
Park brake indicator
-
High beam indicator
Interior Lighting
-
Interior illumination control
-
Delayed illumination
-
Illuminated entry
-
Exit illumination
-
Inadvertent power (battery rundown) protection
Power Door Locks
-
All door unlock
-
All door lock
-
Lockout prevention
Passlock(TM) Theft Deterrent
Passlock(TM) is a vehicle theft deterrent system. This system contains an ignition key sensor called a Passlock(TM) sensor. The Passlock(TM) sensor is
part of the ignition lock cylinder assembly. The BCM provides power and ground for the Passlock(TM) sensor.
When turning the ignition switch to the start position with the proper key, the Passlock(TM) sensor generates an analog voltage signal. This signal is sent
through the Passlock(TM) 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) or the vehicle control module (
VCM), depending on your powertrain option. As a result, the PCM/VCM allows fuel delivery to the engine.
When attempting to start the engine without the proper key in the ignition switch, the Passlock(TM) sensor sends an analog voltage signal of a different
