Inspection Procedure

WARNING: This page is about a different car, the 2004 Lexus ES 330. However, it is still accessible from the selected car via links, so may be relevant.

CHECK CONTINUITY OF COMMUNICATION LINE
1. Check the wire harness between the driver side J/B (body ECU) and theft warning ECU (theft deterrent ECU).
  
  Fig 1: Identifying Driver Side J/B (Body ECU) And Theft Warning ECU
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  1. Disconnect the connectors of the T6 theft warning ECU (theft deterrent ECU) and B5 driver side J/B (body ECU).
  2. Check the continuity between terminal MPX1 (T6-10) of the theft warning ECU (theft deterrent ECU) wire harness side connector and terminal MPX3 (B5-13) of the driver side J/B (body ECU) wire harness side connector.
    Standard: Continuity
    
    NG: REPAIR OR REPLACE WIRE HARNESS AND CONNECTOR
    
    OK: Go to next step.
CHECK THEFT WARNING ECU ASSY (THEFT DETERRENT ECU) (POWER SOURCE)
1. Inspect the ECU power source input.
  1. Disconnect the T6 ECU connector.
  2. Check the voltage between each terminal of the ECU wire harness side connector and the body ground.
    
    Fig 2: Identifying T6 ECU Connector
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    
    Standard:
    
    Fig 3: T6 ECU Connector Voltage Specification Chart
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
NG: REPAIR OR REPLACE FUSE OR WIRE HARNESS AND CONNECTOR

OK: Go to next step.
CHECK THEFT WARNING ECU ASSY (THEFT DETERRENT ECU) (GROUND)
1. Inspect the ECU body ground.
  1. Disconnect the T6 ECU connector.
  2. Check the continuity between terminal E (T6-11) of the ECU wire harness side connector and the body ground.
    
    Fig 4: Disconnecting T6 ECU Connector
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  Standard: Continuity
  
  NG: REPAIR OR REPLACE WIRE HARNESS AND CONNECTOR
  
  OK: REPLACE THEFT WARNING ECU ASSY