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Trouble Shooting

WARNING: This page is about a different car, the 2003 Lexus GS 430, 2003 Lexus GS 300, 2002 Lexus GS 430, and 2002 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.
  1. Trouble shooting of a multiplex communication system complaint begins with verification of the customer problem. If problem occurs, go to step  3. If problem does not occur, go to next step.
  2. If problem does not occur, review conditions under which problem occurred for customer and try to duplicate those conditions. 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.
  3. Perform pre-check. See PRE-CHECK  under SELF-DIAGNOSTIC SYSTEM. If a normal code is retrieved, go to the next step. If a malfunction code is retrieved, perform a circuit inspection. See DIAGNOSTIC TROUBLE CODE INDEX  table.
  4. Determine the problem system.
    • On GS 300 Model (Engine 2JZ-GE). See SELF-DIAGNOSTICS - GS300 article in ENGINE PERFORMANCE.
    • On GS 430 Model (Engine 3UZ-FE). See SELF-DIAGNOSTICS - GS430 article in ENGINE PERFORMANCE.
    • Body No. 1 ECU Control System. See BODY CONTROL SYSTEMS article under COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT.
    • Body No. 2 ECU Control System. See BODY CONTROL SYSTEMS article under COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT.
    • Driver Door System. See the appropriate article for the affected area (power door locks, power windows or power mirrors) of the driver door system.
    • Passenger Door System. See the appropriate article for the affected area (power door locks, power windows or power mirrors) of the passenger door system.
    • Rear Right Door System. See the appropriate article for the affected area (power door locks or power windows) of the rear right door system.
    • Rear Left Door System. See the appropriate article for the affected area (power door locks or power windows) of the rear left door system.
    • Air Conditioning System. See appropriate AUTOMATIC A/C-HEATER SYSTEMS article in HVAC.
    • Power Tilt and Power Telescopic Steering Column. See appropriate POWER TILT & POWER TELESCOPIC STEERING COLUMN article in STEERING.
    • Instrument Panel System. See INSTRUMENT PANEL article in ACCESSORIES & EQUIPMENT.
    • Moon Roof System. See POWER MOON ROOF article under SUN ROOF/T-TOP/CONVERTIBLE TOP in ACCESSORIES & EQUIPMENT.
    • Power Seat System. See POWER & HEATED SEATS article under SEATS in ACCESSORIES & EQUIPMENT.
    • LEXUS Navigation System. Further diagnosis information is not available.
  5. Retrieve DTCs using the OPEN DOOR indicator light. See USING OPEN DOOR INDICATOR LIGHT  under RETRIEVING DIAGNOSTIC TROUBLE CODES.
  6. Retrieve DTCs using the hand-held tester. See USING HAND-HELD TESTER  under RETRIEVING DIAGNOSTIC TROUBLE CODES.
  7. Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES .
  8. After problem has been identified and repaired, confirm repairs. See CONFIRMATION TEST  under SELF-DIAGNOSTIC SYSTEM.
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