Inspection Procedure

WARNING: This page is about a different car, the 2004 Lexus LS 430. However, it is still accessible from the selected car via links, so may be relevant.

CHECK TELEPHONE SWITCH ASSY
1. Disconnect the O6 switch connector.
2. Measure the resistance between the terminals of the switch connector when each switch is pressed.
  Standard:
  
  Fig 1: Tester Specification
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Fig 2: Disconnecting O6 Switch Connector
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
NG: REPLACE TELEPHONE SWITCH ASSY (See MAYDAY SYSTEM )

OK: Go to next step
CHECK WIRE HARNESS (TELEPHONE ECU ASSY - TELEPHONE SWITCH, TELEPHONE SWITCH ASSY - BODY GROUND)
1. Disconnect the A ECU and O6 switch connectors.
2. Measure the resistance between the wire harness side connectors.
  Standard:
  
  Fig 3: Tester Specification
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Fig 4: Disconnecting A ECU And O6 Switch Connectors
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
NG: REPAIR OR REPLACE HARNESS AND CONNECTOR

OK: REPLACE TELEPHONE ECU ASSY (See MAYDAY SYSTEM )