Toyota Corolla (E120) 2002–2008 Repair Manual / Introduction / How to troubleshoot ecu controlled systems / General information

Toyota Corolla (E120): General information

There are many ecu controlled systems used in the corolla. In general, ecu controlled system are considered to be very intricate and require a high level of technical knowledge and expert skill to troubleshoot.

The fact is, however, that if you proceed by inspecting the circuits one by one, troubleshooting of these systems is not complex. If you have adequate understanding of the system and basic knowledge of electricity, the problem can be accurately diagnosed and fixed. This manual is designed based on the above principle to help service technicians perform accurate and effective troubleshooting, and is compiled for the following major ecu controlled systems: the troubleshooting procedures are described on the following pages.

System

1. Sfi system
2.  Abs with ebd system
3.  Electronic controlled automatic transaxle [ect]
4.  Supplemental restraint system
5.  Audio system
6.  Combination meter
7.  Power door lock control system
8.  Wireless door lock control system
9.  Toyota vehicle intrusion protection system
10. Cruise control system

For using hand–held tester

• Before using the tester, the tester’s operator manual should be read thoroughly.
• If the tester cannot communicate with the ecu controlled systems when you have connected the cable of tester to the dlc3, turned the ignition switch on and operated the tester, there is a problem on the vehicle side or tester side.

1.  If the communication is normal when the tester is connected to another vehicle, inspect the diagnosis data link line (bus line) or ecu power circuit of the vehicle.
2.  If the communication is still impossible when the tester is connected to another vehicle, the problem is probably in the tester itself, so perform the self test procedures outlined in the tester operator’s manual.