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 air bag sensor assembly by checking whether or not the DTC is output when changing to other air bag sensor assembly. The results are OK if a DTC is not output. If the results are OK, go to the next step. If the results are not good, replace the air bag sensor assembly (original air bag sensor assembly is failure). Vehicles are equipped with air bag supplemental restraint system. Before attempting any repairs involving steering column, instrument panel or related components, see SERVICE PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM in AIR BAG RESTRAINT SYSTEMS article.
Check the wiring harness by disconnecting the C8 connector of the air bag sensor assembly, C12 of the instrument panel ECU and T5 of the tilt and telescopic ECU. See CONNECTOR IDENTIFICATION .
1. Check the continuity between terminals MPX1 of the air bag sensor assembly and MPX2 of the tilt and telescopic ECU. See WIRING DIAGRAMS .
2. Check the continuity between terminals MPX2 of the air bag sensor assembly and MPX+ of the instrument panel ECU.
If there is an OPEN in the wiring harness of either step (A) or (B), repair it. If continuity exists in the wiring harness of both steps (A) and (B), or either (A) or (B), replace the air bag sensor assembly. Vehicles are equipped with air bag supplemental restraint system. Before attempting any repairs involving steering column, instrument panel or related components, see SERVICE PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM in AIR BAG RESTRAINT SYSTEMS article. If there is not continuity, repair or replace the wiring harness. See WIRING DIAGRAMS .
After repairs have been made, perform confirmation test. See CONFIRMATION TEST under SELF-DIAGNOSTIC SYSTEM.