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Power Source Circuit

  1. Check MPX-B1, MPX-IG and D DOOR fuses. Replace as necessary. If fuses are okay, go to next step.
  2. Turn ignition on. Measure voltage (backprobe) between driver door ECU connector "B" terminals No. 1 (White/Black wire) and No. 5 (Red/Blue wire). See Fig 1. Battery voltage should be present. Turn ignition off. Disconnect driver door ECU connector. Measure voltage between connector terminals No. 1 (White/Black wire) and No. 4 (Violet/Yellow wire), and between terminals No. 1 (White/Black wire) and No. 6 (Red wire). Battery voltage should be present. If voltages are not to specification, go to next step. If voltages are to specification, check driver door ECU. See BODY CONTROL SYSTEMS - LS430 and MULTIPLEX CONTROL SYSTEMS - LS430 articles.
  3. If voltages are not to specification, check wiring harness and connectors between master switch and driver door ECU, and between ECU and ground. See WIRING DIAGRAMS . Repair wiring as necessary.
    Fig 1: Identifying Driver Door ECU Connector Terminals
    G00020627Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002