I have an '05 Civic EX special edition with a problem. When I switch on the rear window defogger, the radio volume decreases and the reception turns to about 50% static. I looked on the wiring diagram and the defogger and radio share a common thread - the antenna module. They both plug into it. There is an am antenna and the rear defogger IS the fm antenna. I was wondering if anyone here has ever had problems with the antenna module and had to replace it? I'm not sure if that's the problem. When it warms up (current temp is 5*) I'm going to clean the wire connections at the plugs on the module to see if that helps. Other than that, I'm at a total loss. Any ideas? Thanks.
Duane

 

There may be a gap or a bad connection in the defogger grid itself causing it to generate RF noise that interferes with the radio. Do all of the grid wires heat up? Are there any "hot spots" (little circular areas around one wire that defog much faster than the rest of the window)?

Another test uses a battery-powered transistor radio (remember those?). Turn the defogger on, tune in an AM station, and move the radio around the window listening for noisy spots.

Minor breaks in the grid can be patched with conductive paint.

 

do you have window tints ???

 

I'm going to do the transistor radio check if the temp ever gets up to 30* again. That may help eliminate the possibility of a broken wire. I visually checked and don't see any problem areas, but that's not always the case.
I don't have any window tint, either. The car is just as I bought it in 2005. When I wash the inside of the back window, I am very careful of the defroster strips, but I could have damaged something and not known it. I'll find out when I do the radio test. Thanks for the suggestions. When I figure out what it is that's causing the interference, I'll post back in case anyone else has the same trouble.
Duane