Description & Operation

NOTE: This article covers procedures for body control system as well as driver door control system and passenger door control system. Driver door control system and passenger door control system may be referenced when using this article.

WARNING: Vehicle is equipped with air bag supplemental restraint system. Before attempting ANY repairs involving steering column, instrument panel or related components, see SERVICE PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM in appropriate AIR BAG RESTRAINT SYSTEMS article.

Body control system controls the following systems: key unlock warning system and buzzer, headlights, taillights, automatic turn off system for interior lighting, interior lights, seat belt warning indicator, open door warning indicator, power windows, power door locks, trunk opener system, power mirrors, keyless entry system and horn system. Body Electronic Control Unit (ECU) is connected to a multiplex communication system with theft-deterrent ECU, driver's door ECU, passenger's door ECU and power seat ECU. This communication system is referred to as the multiplex control system. Before starting any diagnosis on body control system components or circuits, check multiplex control system operation to ensure that all ECUs are able to communicate with each other. See MULTIPLEX CONTROL SYSTEMS - AVALON article.

Driver door and passenger door control systems are used to control the following systems on each respective door: power window, power door lock and power mirror. Driver's door ECU and passenger's door ECU is connected to a multiplex communication network with theft-deterrent ECU, power seat ECU and body ECU. This communication system is referred to as the multiplex control system. Before starting any diagnosis on driver door or passenger door control system components or circuits, check multiplex control system operation to ensure that all ECUs are able to communicate with each other. See MULTIPLEX CONTROL SYSTEMS - AVALON article.