Inspection Procedure

WARNING: This page is about a different car, the 2007 Lexus SC 430. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT TELEPHONE MICROPHONE

Disconnect the P12 microphone connector.

Fig 1: Identifying P12 Microphone Connector Terminals
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Measure the resistance of the microphone.

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION CHART

Tester Connection	Specified Condition
2 - 7	Approx. 750 Ω

NG: REPLACE TELEPHONE MICROPHONE

OK: Go to next step

CHECK WIRE HARNESS (TELEPHONE MICROPHONE AMPLIFIER - TELEPHONE MICROPHONE AND MULTI-DISPLAY)

Disconnect the M7 and M8 amplifier connectors.

Fig 2: Identifying M7 And M8 Amplifier Connectors Terminals
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Disconnect the M6 display connector.
Disconnect the P12 microphone connector.

Measure the resistance of the wire harness side connectors.

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION CHART

Tester Connection	Specified Condition
M8-2 (MIC-) - P12-7	Below 1 Ω
M8-4 (MIC+) - P12-6	Below 1 Ω
M7-4 (MIC+) - M6-5 (MIN+)	Below 1 Ω
M7-2 (MIC-) - M6-6 (MIN-)	Below 1 Ω
M7-5 (MACC) - M6-7 (MACO)	Below 1 Ω
M8-4 (MIC+) - Body ground	Below 1 Ω
M7-2 (MIC-) - Body ground	Below 1 Ω
M7-4 (MIC+) - Body ground	Below 1 Ω
M7-5 (MACC) - Body ground	Below 1 Ω

NG: REPAIR OR REPLACE HARNESS AND CONNECTOR

OK: Go to next step

INSPECT INSTRUMENT CLUSTER FINISH PANEL CENTER

Remove the instrument cluster finish panel center.

Fig 3: Identifying Instrument Cluster Finish Panel Center Connector Terminals
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Measure the resistance of the panel.

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION CHART

Tester Connection	Specified Condition
M6-7 (MACO) - B-6 (MACO)	Below 1 Ω
M6-5 (MIN+) - B-4 (MIN+)	Below 1 Ω
M6-6 (MIN-) - B-5 (MIN-)	Below 1 Ω
M6-7 (MACO) - Body ground	10 kΩ or higher
M6-5 (MIN+) - Body ground	10 kΩ or higher
M6-6 (MIN-) - Body ground	10 kΩ or higher

NG: REPAIR OR REPLACE INSTRUMENT CLUSTER FINISH PANEL SUB-ASSEMBLY CENTER

OK: Go to next step

CHECK OPERATION OF TELEPHONE MICROPHONE AMPLIFIER
1. Replace the telephone microphone amplifier with a normal one.
2. Check that the ignition switch can be turned ON and that voice recognition is normal.
  OK:
  
  Voice is recognition is normal.
NG: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN DIAGNOSTIC TROUBLE CODE CHART

OK: END (REPLACE TELEPHONE MICROPHONE AMPLIFIER)