Test Procedure
WARNING: This page is about a different car, the 2003 Lexus ES 300 and 2002 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
- Disconnect the anti-theft ECU connector. Measure the voltage between ground and terminal +B1 (T6-2) of anti-theft ECU connector. See Fig 1. If voltage is 10-14 volts, go to UNLOCK WARNING SWITCH CIRCUIT (KEY UNLOCK WARNING SYSTEM) under POWER DOOR LOCKS, TRUNK LID & FUEL DOOR RELEASE - ES 300 article under DOOR LOCKS & ANTI-THEFT SYSTEMS in ACCESSORIES & EQUIPMENT. If the voltage is not 10-14 volts, go to the next step.
- Check the continuity between terminal E (T6-11) of the anti-theft ECU and body ground. See Fig 2. If continuity exists, check and replace the anti-theft warning ECU assembly. If continuity does not exist, repair and replace wire harness or connector as necessary.