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 FUSE (DC CUT, AM2, MPX-B2, MAYDAY, RRACC)
1. Remove the DC CUT fuse from the FL block.
2. Remove the MAYDAY, MPX2 and AM2 fuses from the passenger side J/B.
3. Remove the RR ACC fuse from the luggage room J/B.
4. Measure the resistance.
  Standard: Below 1 Ω
NG: REPLACE FUSE

OK: Go to next step
CHECK WIRE HARNESS (TELEPHONE ECU ASSY - BODY GROUND)
1. Disconnect the A ECU connector.
2. Measure the voltage of each terminal of wire harness side connector.
  Standard:
  
  Fig 1: Tester Specification
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Fig 2: Disconnecting A ECU Connector
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Measure the resistance between the A ECU connector and body ground,
  Standard:
  
  Fig 3: Tester Specification
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
NG: REPAIR OR REPLACE HARNESS AND CONNECTOR

OK: REPLACE TELEPHONE ECU ASSY (See MAYDAY SYSTEM )