Self-Diagnostic System: Pre-Check
WARNING: This page is about a different car, the 2002 Lexus LX 470. However, it is still accessible from the selected car via links, so may be relevant.
- Diagnosis System
- Each ECU of this vehicle is connected by communication bus and it transmits each signal by communication. This communication bus is self-diagnosed by the Body ECU and it memorizes the DTC when it detects communication stop to the ECU or communication bus +B short or GND short. There is a possibility that the Body ECU cannot self-diagnose accurately if it doesn't work normal. Confirm that the Body ECU and open door indicator work normally before trouble shooting the body electrical system.
- If the DTC of ECU communication stop is output, there is a possibility of connector disconnection or 2 communication buses open. See Fig 1. It will not become abnormal with only 1 communication bus open.
- If 2 communication buses are open at the position, the DTC of ECU communication stop between those 2 buses is output. See Fig 2.
- Basic Inspection
- Inspect the body No. 1 ECU operation. With this inspection, the body ECU can be diagnosed if it works normal or not. Check if the luggage compartment door opener works normally. If the results are OK, go to step 3. If the results are not good, go to the next step.
- Check the rear wiper system (except body No. 1 ECU). See WIPER/WASHER & HEADLIGHT CLEANER SYSTEMS article under WIPER/WASHER SYSTEMS in ACCESSORIES & EQUIPMENT. If the results are OK, replace the body ECU. See BODY ECU (INSTRUMENT ECU) under REMOVAL & INSTALLATION. If the results are not good, repair or replace the malfunction part.
- Open Door Indicator Light Inspection
Check if the open door indicator light is turned on when either door open. If the open door indicator light is not turned on, DTC will not be output. If the results are OK, go to USING INDICATOR LIGHT under RETRIEVING DIAGNOSTIC TROUBLE CODES. If the results are not good, repair the open door indicator light. See INSTRUMENT PANEL article in ACCESSORIES & EQUIPMENT.