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.

CHECK OPERATION (STEERING PAD SWITCH)
1. Check that the steering pad switch can operate the audio system normally.
  OK: Steering pad switch can operate the audio system normally.
OK: REPLACE RADIO RECEIVER ASSEMBLY

NG: Go to next step.

CHECK RESISTANCE OF COMMUNICATION LINE

Disconnect the G3 ECU connector.
Disconnect the R1 receiver connector.

Fig 1: Identifying G3 ECU Connector And R1 Receiver Connector
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Measure the resistance of the wire harness side connectors.

Standard resistance

RESISTANCE SPECIFICATION

Tester Connection	Specified Condition
R1-3 (TXS+) - G3-9 (GTX+)	Below 1 Ω
R1-6 (TXS-) - G3-20 (GTX-)	Below 1 Ω

Result

RESULT CHART

Result	Proceed to
Both are OK	A
One is OK	B
Both are NG	C

B: REPLACE RADIO RECEIVER ASSEMBLY AND REPAIR OR REPLACE HARNESS AND CONNECTOR

C: REPAIR OR REPLACE HARNESS AND CONNECTOR

A: REPLACE RADIO RECEIVER ASSEMBLY