General Information

GENERAL INFORMATION
A large number of ECU controlled systems are used in the TOYOTA TUNDRA. In general, ECU controlled systems are considered to be a very intricate, requiring a high level of technical knowledge to troubleshoot. However, following the problem checking procedures of the ECU controlled system's circuits carefully is not complex. If you have an adequate understanding of the system and a basic knowledge of electricity, accurate diagnosis and necessary repair can be performed.

This manual emphasizes the above standpoint to help service technicians perform accurate and effective troubleshooting.

FOR USING OBD II SCAN TOOL OR HAND-HELD TESTER
- Before using the tester, read its user manual thoroughly.
- Connect the cable of the tester to DLC3, turn the ignition switch ON and operate the tester. If the tester cannot communicate with the ECU controlled system, there is a problem on the vehicle side or tester side.

1. If 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 communication is still not possible when the tester is connected to another vehicle, the problem lies in the tester. Perform the Self Test procedures outlined in the Tester Operator's Manual.