Inspection Procedure

WARNING: This page is about a different car, the 2007 Lexus GX 470. However, it is still accessible from the selected car via links, so may be relevant.

CHECK NAVIGATION SYSTEM
1. Start the navigation system and check that the voice recognition microphone function operates normally.
  1. If the microphone function is normal, proceed to A.
  2. If the microphone function is malfunctioning, proceed to B.
  B: GO TO NAVIGATION SYSTEM (See HOW TO PROCEED WITH TROUBLESHOOTING )
  
  A: Go to next step

CHECK WIRE HARNESS (MAYDAY ECU ASSEMBLY - ROOF CONSOLE BOX ASSEMBLY)

Fig 1: Identifying Roof Console Box & Mayday ECU Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Disconnect the M15 ECU connector.
Disconnect the O2 roof console box connector.
Measure the resistance of the wire harness side connectors.
Standard resistance

RESISTANCE SPECIFICATION

Tester Connection	Specified Condition
M15-7 (TACC) - O2-9 (MACC)	Below 1 Ω
M15-7 (TACC) or O2-9 (MACC) - Body ground	10 kΩ or higher

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to next step

CHECK WIRE HARNESS (ROOF CONSOLE BOX ASSEMBLY - BODY GROUND)

Fig 2: Identifying Roof Console Box Connector Terminals

Disconnect the O2 roof console box connector.
Measure the resistance of the wire harness side connector.
Standard resistance

RESISTANCE SPECIFICATION

Tester Connection	Specified Condition
O2-4 (GND) - Body ground	Below 1 Ω

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to next step

REPLACE ROOF CONSOLE BOX ASSEMBLY
1. Temporarily replace the roof console box assembly (See MAYDAY SWITCH ) with a new or normally functioning one.
2. Check that the DTC 4-3 is output.
  OK:
  
  DTC 4-3 is not output.
  
  NOTE: If replacement of the ECU is necessary, replace the mayday battery (backup battery) together with the ECU. After the replacement, register the ECU (See REGISTRATION ).
  
  NG: REPLACE MAYDAY ECU ASSEMBLY (See REMOVAL )
OK: END