Defogger Switch Test: LS400

WARNING: This page is about a different car, the 1992 Lexus SC 400, 1992 Lexus SC 300, 1992 Lexus LS 400, and 1992 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.

Remove A/C control panel assembly. See A/C CONTROL PANEL ASSEMBLY under REMOVAL & INSTALLATION. Connect battery voltage to terminal No. 2 and ground to terminal No. 9. Connect 1.4 watt-test light between terminals No. 2 and 8.
Place switch in ON position. Ensure test light comes on for approximately 15 minutes and then goes out. If switch does not operate as specified, replace A/C control panel assembly. See Fig 1.

Fig 1: Testing Rear Defogger Switch (LS400)