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 WIRE HARNESS (TELEPHONE ECU ASSY - TELEPHONE TRANSCEIVER ASSY)
1. Disconnect the A ECU and G transceiver connectors.
2. Measure the resistance between wire harness side connectors.
Standard:

Fig 1: Tester Specification
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 2: Disconnecting A ECU And G Transceiver Connectors
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG: REPAIR OR REPLACE HARNESS AND CONNECTOR

OK: Go to next step
CHECK WIRE HARNESS (TELEPHONE ECU ASSY - TELEPHONE SWITCH ASSY, 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
CHECK MICROPHONE ASSY
1. Check that the malfunction disappears when a normal microphone is installed (see MAYDAY SYSTEM ).
  1. If the malfunction does not disappear, proceed to A.
  2. If the malfunction disappears, proceed to B.
  B: REPLACE MICROPHONE ASSY (See MAYDAY SYSTEM )
  
  A
2. CHECK MICROPHONE AMPLIFIER ASSY
  1. Check that the malfunction disappears when normal microphone amplifier is installed (see MAYDAY SYSTEM ).
    1. If the malfunction does not disappear, proceed to A.
    2. If the malfunction disappears, proceed to B.
    B: REPLACE MICROPHONE AMPLIFIER ASSY (See MAYDAY SYSTEM )
    
    A: Go to next step
  2. CHECK TELEPHONE TRANSCEIVER ASSY
    1. Check that the malfunction disappears when a normal telephone transceiver is installed (see MAYDAY SYSTEM ).
      1. If the malfunction does not disappear, proceed to A.
      2. If the malfunction disappears, proceed to B.
      B: REPLACE TELEPHONE TRANSCEIVER ASSY (See MAYDAY SYSTEM )
      
      A: Go to next step
      
      REPLACE TELEPHONE ECU ASSY (See MAYDAY SYSTEM )