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GBurton
10-23-2003, 22:12
I think this is a new one, at least I don't think it's been talked about here.

A couple of weeks ago on a trip my wife was driving while I tried to get some rest. I kept hearing what I thought was tire noise. After listening to it for a few minutes I noticed that it seemed to be coming from the right door speaker. I checked and the radio was turned off. I covered the speaker with a jacket and the volume went down. I then started timing it, about 10 seconds on and 10 seconds off. I had my wife change speed and put it in neutral while we were moving, no change. When there was no nearby traffic I even had her put it in neutral and carefully shut off the key. That stopped the noise. Restarted the engine and continued on the trip. Some times the noise is there and some times it's not.
When it's audible it sounds like it is a combination of several tones but all around the 800 Hz range. Kind of like a high pitched foghorn. It does not change pitch with a change of engine RPM like an alternator would do.

Any ideas??

George

NWDmax
10-24-2003, 00:34
Plug wires tongue.gif tongue.gif tongue.gif

SDWA
10-24-2003, 07:18
Turn the A/C off if it's on, and make sure you're vent selector is on floor only (no defrost) and see if you still hear it. If you don't, then turn the A/C back on and you should hear it as soon as you press the A/C button.

I'll bet it's your A/C compressor cycling. I've heard it on several trucks, but only when I sit in the passenger seat... And "foghorn" describes it perfectly!

Scott

BigLakeDMAX
10-24-2003, 10:01
Couple of thoughts - I believe I heard that the stereo amps in these trucks are powered constantly (when key is on and within delay time after key turned off) so turning the radio off will not turn off the amps or power to the speakers. Also, the stereo has its own thermostatically controlled cooling fan that emits an audible, high pitched tone. This fan cycles on and off and will also remain on after the radio is turned off and/or with the key off until you open a door. You can then hear it wind down. The fan is totally unaffected by engine or truck speed.

If it is actually coming from your door speaker, it may be electrical noise from the fan or amps. The fan noise is somewhat deceptive as it seems to come from everywhere unless you really get your ear close to the stereo where it definitely seems louder.

HD-Nate
10-24-2003, 12:28
I