SC300 & SC400

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 A6 and ground terminal A7. Connect battery voltage, through a 1.4 watt test bulb, to terminal B10. See Fig 1.

Fig 1: Testing Rear Defogger Switch (SC300 & SC400)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Place defogger switch in ON position. Ensure test light and indicator light illuminate for approximately 15 minutes and then go out. If switch does not operate as specified, replace A/C control panel assembly.