General Description

BODY CONTROL MODULE GENERAL DESCRIPTION
Familiarize yourself with the information and proper diagnosing procedures before using this section of the manual. This section contains a Body Control Module (BCM) diagnostic system check. 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.

BODY CONTROL MODULE SYSTEM DESCRIPTION
The BCM is designed in order to perform the following functions:
^ Process various input information
^ Send the needed electrical responses to the other control modules

The input information is related to more than one output. If one input fails, the failure may affect the operation of more than one system.

The BCM controls the operation of the following components:
^ The audible reminders
^ The warnings
^ The power door locks
^ Interior lighting
^ Exterior lighting

The BCM has features that permit the following functions:
^ Timing out and turning OFF inadvertent loads
^ Providing retained accessory power The BCM is designed in order to interface with a Remote Function Actuator (RFA) subsystem. The interface provides remote operation of certain features of the vehicle. The BCM also provides vehicle security with an integrated PasslockTM system.

The BCM communicates via a Class 2 serial data bus. The communication enables diagnosis and programming at the assembly plant or an approved service center.

The BCM supplies a buffered voltage to various sensors and switches through an internal resistance in the BCM. The resistance is so high in value that an ordinary test lamp may not light when the lamp is connected to the circuit. An ordinary shop voltmeter may give an inaccurate reading because the voltmeter input impedance is too low. Use a J 39200 Digital Multimeter (DMM) in order to ensure accurate voltage readings. Refer to Special Tools.