Diagnostic Procedure

WARNING: This page is about a different car, the 2003 Lexus GS 430, 2003 Lexus GS 300, 2002 Lexus GS 430, and 2002 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.

Check the steering pad switch by turning the ignition switch ON and check that the steering pad switch operate normally. If the results are OK, go to the next step. If the results are not good, replace the steering pad switch. See appropriate POWER TILT & TELESCOPIC STEERING COLUMN article in STEERING.
Check the wiring harness by disconnecting the G6 connector of the gateway ECU, A13 of the A/C amplifier ECU, T5 of the tilt and telescopic ECU and C15 of the steering pad switch. See CONNECTOR IDENTIFICATION .
1. Check the continuity between terminals MPX1 of the steering pad switch and MPD1, MPD2 of the gateway ECU. See WIRING DIAGRAMS .
2. Check the continuity between terminals MPX1 of the steering pad switch and MPX- of the A/C amplifier.
3. Check the continuity between terminals MPX1 of the steering pad switch and MPX1 of the tilt and telescopic ECU.
If there is an OPEN in the wiring harness of any terminals, repair it. If there is continuity in the wiring harness of both steps (A) and (B) or (A) and (C), or either (B) or (C), replace the steering pad switch. See appropriate POWER TILT & TELESCOPIC STEERING COLUMN article in STEERING. If there is not continuity as specified, repair or replace the wiring harness. See WIRING DIAGRAMS .
After repairs have been made, perform confirmation test. See CONFIRMATION TEST under SELF-DIAGNOSTIC SYSTEM.