Body Control System
NOTE:
Prior to trouble shooting body control system, check multiplex communication system for proper operation and stored codes. The body control ECU stores Diagnostic Trouble Codes (DTCs) for the multiplex communication system and is the access point to communicate with other ECUs on the multiplex communication bus (circuit). See MULTIPLEX CONTROL SYSTEMS - AVALON
article under COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT.
- Trouble shooting of a body control system complaint begins with verification of the customer problem. Perform Customer Problem Analysis (Body Control System Check List). See Fig 1. If problem occurs, go to step 3. If problem does not occur, go to next step.
- If problem does not occur, review conditions under which problem occurred for customer. For example, if the problem occurs on rainy days or during high humidity conditions, sprinkle water onto vehicle and see if malfunction occurs. DO NOT sprinkle water directly into engine compartment or onto electronic components. Visually inspect for signs of mechanical and electrical damage. Inspect for blown fuses and damaged relays. Inspect for loose or corroded connections, damaged wiring harnesses and/or switches. Check for a broken or partially broken wire inside insulation, which could cause system malfunction but prove good in a continuity/voltage check with system disconnected. Ensure any aftermarket electronic equipment is properly installed. If fault is found, repair as necessary. If problem still cannot be created, go to next step.
- Ensure multiplex communication system is operating correctly and no faults are present by performing basic inspection and checking for multiplex communication system Diagnostic Trouble Codes (DTCs). See BASIC INSPECTION and RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM under MULTIPLEX CONTROL SYSTEMS - AVALON article under COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT. If multiplex communication system is operational and no DTCs are present, go to next step. If multiplex communication system is not operational or DTCs are present, repair multiplex communication system and retest.
- When proper communication with multiplex control system is established, trouble shoot appropriate body control system by symptom and perform associated test. See BODY CONTROL SYSTEM under SYSTEM TESTS. When performing trouble shooting for body control system, it may be necessary to perform pin voltage tests on body control ECU to ensure proper voltage or input/output signals exist. See BODY CONTROL ELECTRONIC CONTROL UNIT under PIN VOLTAGE TESTS when directed by trouble shooting procedure.
- After problem has been identified and repaired, confirm repairs have resolved complaint. See CONFIRMATION TEST under SYSTEM TESTS.