GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 GMC K Sierra - 4WD 🢒 Body and Accessories 🢒 Stationary Windows 🢒 Defogger System Check

Step

Action

Normal Result(s)

Abnormal Result(s)*

1
    • Turn the ignition switch to the RUN position.
    • Press the rear defogger switch.

The rear defogger LED will light, and both the grid and the outside mirrors will get warm. After approximately 10 minutes the system will turn OFF.
    • Indicator does not light, the grid does not warm. Refer to Rear Window Defogger Inoperative .
    • Indicator lights, the grid does not warm. Refer to Rear Window Defogger Inoperative .

2
    • Turn the ignition switch to the RUN position.
    • Press the rear defogger switch.

The outside mirrors will get warm.

Outside mirrors do not warm. Refer to Heated Mirrors Inoperative in Doors.