Toyota Yaris: How To Troubleshoot Ecu Controlled Systems / General Information

• A large number of ECU controlled systems are used in this vehicle. In general, ECU controlled systems are considered to be very intricate, requiring a high level of technical knowledge to troubleshoot. However, most problem checking procedures only involve inspecting the ECU controlled system circuits one by one. An adequate understanding of the system and a basic knowledge of electricity is enough to perform effective troubleshooting, accurate diagnosis and necessary repairs.

• When using the GTS
  • Before using the GTS, read the operator's manual thoroughly.
  • If the GTS cannot communicate with the ECU controlled systems when connected to the DLC3 with the ignition switch ON and the GTS on, there is a problem on the vehicle side or the GTS side.
    1. If communication is possible when the GTS is connected to another vehicle, inspect the diagnosis data link line (bus (+) line), CANH and CANL lines, and the power source circuits of the vehicle ECUs.
    2. If communication is still not possible when the GTS is connected to another vehicle, the problem is probably in the GTS itself. Perform the Self Test procedure outlined in the GTS operator's manual.

• The troubleshooting procedures consist of diagnostic procedures for when a DTC is stored and diagnostic procedures for when no DTCs are stored. The basic idea is explained in the following table.

  Procedure Type	Details	Troubleshooting Method
  DTC Based Diagnosis	The diagnostic procedure is based on the DTC that is stored.	The malfunctioning part is identified based on the DTC detection conditions using a process of elimination. The possible trouble areas are eliminated one-by-one using the GTS and inspection of related parts.
  Symptom Based Diagnosis (No DTCs stored)	The diagnostic procedure is based on problem symptoms.	The malfunctioning part is identified based on the problem symptoms using a process of elimination. The possible trouble areas are eliminated one-by-one using the GTS and inspection of related parts.

• Vehicle systems are complex and use many ECUs that are difficult to inspect independently. Therefore, a process of elimination is used, where components that can be inspected individually are inspected, and if no problems are found in these components, the related ECU is identified as the problem and replaced.
• It is extremely important to ask the customer about the environment and the conditions present when the problem occurred (Customer Problem Analysis). This makes it possible to simulate the conditions and confirm the symptom. If the symptom cannot be confirmed or the DTC does not recur, the malfunctioning part may not be identified using the troubleshooting procedure, and the ECU for the related system may be replaced even though it is not defective. If this happens, the original problem will not be solved.
• In order to prevent endless expansion of troubleshooting procedures, the troubleshooting procedures are written with the assumption that multiple malfunctions do not occur simultaneously for a single problem symptom.
• To identify the malfunctioning part, troubleshooting procedures narrow down the target by separating components, ECUs and wire harnesses during the inspection. If the wire harness is identified as the cause of the problem, it is necessary to inspect not only the connections to components and ECUs but also all of the wire harness connectors between the component and the ECU.

How To Troubleshoot Ecu Controlled Systems

..

Electronic Circuit Inspection Procedure

ELECTRONIC CIRCUIT INSPECTION PROCEDURE BASIC INSPECTION (a) WHEN MEASURING RESISTANCE OF ELECTRONIC PARTS (1) Unless otherwise stated, all resistance measurements are standard values measured at an ambient temperature of 20°C (68°F)...

Other information:

Toyota Yaris XP210 (2020-2024) Reapir and Service Manual: Freeze Frame Data

FREEZE FRAME DATA DESCRIPTION The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was moving or stationary, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction...

Toyota Yaris XP210 (2020-2024) Reapir and Service Manual: Installation

INSTALLATION CAUTION / NOTICE / HINT HINT: Use the same procedure for the RH side and LH side. The following procedure is for the LH side. PROCEDURE 1. INSTALL CURTAIN SHIELD AIRBAG ASSEMBLY NOTICE: When installing a curtain shield airbag assembly, have assistants hold it to prevent it from bending...