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I drove my 85LTC out to a park enjoying some delightful Spring weather in Seattle today, everything running fine. On the way home I suddenly heard a semi-loud high frequency noise in the cabin. It quickly became apparent it was rising and falling exactly with the engine speed, but it sounded as if it were being made electronically.
I had heard something like it on an old Buick that had faint feedback through the radio. I turned off the radio to make sure it wasn't that, but the volume was just the same, seeming to come from the dash. After about 10 minutes I went over a bump and it stopped, then came back. During the 10 mile drive it sort of came and went according to bumps in the road, always following the pitch of the engine speed, sometimes rather loud, sometimes very faint.
My only guess is some kind of bad connection or feedback throught the attention chime of the electronic message center.
It is loud enough to be quite annoying; any help is appreciated.
Posted by: CobraConti
this is easy to explain unfortunately i don't remember the exact reason! ahha. I used to know this years ago. Seriously, trying to jiggle my brain here, it has something to do with electronic interference coming from the alternator interfering with your radio or something like that. This is a common problem on older cars with aftermarket stereos. Somebody else will know this easy. Or google "radio whine" or "alternator whine" and see what comes up.
Posted by: corey85TC
I'll check the reference you mentioned for general info, but I'm sure it is NOT a problem with the factory radio.
The noise was still there when the radio was off and not there at all some of the time, radio on or off, which is not what happens with RF interference. It seemed to be coming from the dash, not from any of the speakers.
As would happen it didn't happen at all today when I drove it, but I have a feeling it is some kind of intermitttent loose or crossed wire that will be back soon enough.
Posted by: corey85TC
I miss spoke, it is RF interference, probably from the ignition or alternator, but it isn't coming through the radio.
