: Very strange radio static interference – need help



midnightrider
10-02-09, 04:33 PM
I did a search and could not find help with this.

When I turn on the rear defrost I receive static on a few radio stations. Once I turn off the rear defrost it immediately goes away.

Has anyone ever had or heard of this problem? Is there a fix for it? It seems very strange especially since it only seems to affect a few stations.

N*Caddy
10-04-09, 10:59 AM
Well one of the radio antennas is installed on the same glass with the rear defrost grid while the other is on the windshield (not sure witch one is where) but if the static happens on FM then is the FM antenna in the back if not is the AM. There is a module that switches between the two antennas based on the radio command.
Do you have tinted windows, stickers and such and the static started about in the same time. In any case I would start with a very good cleanup of the rear glass (caution not to damage the defrost grill and antenna).

midnightrider
10-05-09, 11:25 AM
Well one of the radio antennas is installed on the same glass with the rear defrost grid while the other is on the windshield (not sure witch one is where) but if the static happens on FM then is the FM antenna in the back if not is the AM. There is a module that switches between the two antennas based on the radio command.
Do you have tinted windows, stickers and such and the static started about in the same time. In any case I would start with a very good cleanup of the rear glass (caution not to damage the defrost grill and antenna).

Thanks N*Caddy for the replay.

I have the power antenna that is separate from the rear glass. So do you think it still has something to do with the rear window?

I will go ahead and do a extra deep cleaning of the rear window. Also, I do not have tinted windows or any stickers/decals on the glass. But I will definitely try a deep cleaning.

Any other suggestions?

Submariner409
10-05-09, 01:44 PM
Check the hot and ground terminal connections for the power cables to the rear window heater grid. A loose/corroded connector will cause DC "hash" in the radio circuits, with the interference occurring on the radio stations close to the same frequency as the "hash". Another (remote) possibility is that the window heater circuit is picking up some fuel pump whine or other electrical interference.

Be real careful with those window connector tabs - any sort of glues does not stick to glass very well, so go easy.

N*Caddy
10-05-09, 08:56 PM
Oh ups, didn’t noticed the Eldorado thing…
So check the inside the passenger side rear quarter under the liner (where the power antenna is). Locate the braided ground strap between the antenna and the car body. That shield is welded on the antenna body and the other end is a ring lug attached with a screw to the car body. Check is the contact where the ring lug is attached is still good and also make sure the braided strap is still attached to the antenna body.
Other places to look for, well the rear glass heater wire is running parallel for about 2 feet with the antenna cable. Also check if the antenna cable is attached correctly to the back of the HU. After that…I am lost, maybe the filter circuit in the HU is gone (consists of a diode a line filter and a 1000uF 16V capacitor, that capacitor is most likely to go). Tinted windows have nothing to do in your setup.

keelerdr
12-29-09, 02:58 PM
Hey midnightrider,

There was a TSB (Technical Service Bulletin) released for this. It involves the rear window defroster and the "fix" is to get this liquid stuff that you apply over the original defroster lines on the inside of the rear glass and then the liquid hardens and this fixes the problem. I believe it has something to do w/the current running through the defroster wires and if you have the static problem it means the "wires" on the glass are cracked/damaged.

The TSB # is: 03-08-44-005H

and here is a link that has the details:
http://www.gmcentral.com/forum/showthread.php?t=19


Hope this helps.