Audio Systems: FM Signal not received but AM is A-OK!!, fm tuner module, antenna wire

Question
My girlfriend's stock car stereo is not receiving any fm signals (no fm stations are transmitting a signal. If you press seek it doesn't stop until you stop it manually. Not one single frequency across the spectrum is working)  but am signals are coming in fine. I checked the wire at the antenna and it's plugged in. I'm not sure if fm uses a different antenna but in my truck both the fm and am signals die out when I unplug my (one and only) antenna wire. She said it just went out all of a sudden and I'm wondering why this is happening since the antenna is plugged in at both sides. Is there some circuit within the radio that has gone bad? It's a 94 dodge stratus with the stock system. I'm thinkin a wire came loose somewhere or something of that nature but I'd hate to have to take the dash down to look so I want to know what might cause something like that to happen and what the options are, or if it's specific maybe how to fix it.


Answer
Hello Chris,
If the AM section is receiving the antenna is OK. The problem is with the FM tuner inside the stereo. It may only be due to a defective solder connection at the FM tuner module. On a few of these early Dodge stereos, I have found a shorted capacitor in the FM power feed line to the FM tuner. This will cut off the voltage to the FM tuner module and NO fm stereo.

TOM,
T&D ELECTRONICS
tdeser@zoominternet.net