Body Control Module: Description and Operation

PURPOSE
The central processing unit (CPU) monitors and/or controls the operation of several vehicle accessory circuits.

OPERATION
The CPU's relationship with the engine control system is as follows.
An electric load (E/L) signal is generated by the CPU when ever any of the following CPU monitored circuits are operated.
- Blower Motor
- Front Fog Lights
- Head Lights
- Rear Window Defroster

The E/L signal exits the CPU through output terminal 2C and enters the engine control module (ECM) through input terminal 1J.
This E/L signal is used by the ECM as an input for the idle speed control system which compensates for engine load variations and maintains proper engine idle speed.