2003 Grand AM GT rear defrost not working

[lilniemo]

I have been noticing over the past 2 weeks the rear defrost hasn't been working. I'm not sure if it has to do with window tint being put on back in June or not as I cannot recall if I've had to use the rear defrost since then. With the weather getting cold up here and daily frost on the windows I really need to get this fixed ASAP. Any suggestions what to check first? I'm pretty car savvy if anyone can help me I'm sure I'd be able to fix it myself. Thanks much!

[maxwedge]

Welcome to AF. With a test lite find a ground and check for voltage in the wires in the glass, some may be dim this is normal, don't scratch the lines!! If you have voltage, find the ground side of the glass connection and use this ground for the test lite, if no voltage the glass has grounding issue . If no voltage at all, find the relay and check that.

[BNaylor]

Sounds like whoever installed the window tint may have damaged the defogger grid. You can disconnect the connector at the right rear C-pillar and ohm it out to check for continuity. Another possibility which would be coincidental is the RF Filter Module has gone bad. The filter module is a common problem on GM "N" Body cars like the Grand Am and Alero, etc.

The defogger relay is located in the engine compartment fuse box. When pressing the defog button just feel or listen for a click which means it is most likely energizing but that does not guarantee the output which feeds to the filter first before it gets to the grid is good. Good luck.