Help - Speedometer Cable Noise

[RAton]

OK I know there is no speedometer cable but there is a noise coming from my dash that starts at 57 mph and sounds like a cable that needs to be lubed. It’s sound doesn’t change with window open (thinking windshield leak), radio off (thinking electrical noise), pushing on dash (thinking something lose). Anyone else experience this or have any suggestions for me to check? It isn’t real loud just annoying as it comes from right in front of me as I drive. I’ve been up to 80 mph and sound doesn’t change.

 

[HBarlow]

I think our speedometers are electric - driven by an electrical signal tapped off an electromagnet on the rear ring gear. If the noise you are inquiring about changes frequency with road speed the speedometer itself may be failing. If, as you seemed to be saying. the sound doesn't change up to 80 mph it is something else.

 

[RAton]

Thanks Harvey, for the reply. That's the problem there are thousands of "something" elses. Hoping someone else may have had this problem and had a fix.

 

[DE Jeeper]

I remember seeing a tsb on a rivoted id tag somewhere near the windshield that would vibrate at speed or because of wind causing a similar noise. It migt be worth a search??



Aaron

 

[RAton]

Thanks Aaron, I'll check it out.

 

[RAton]

Finally found what the noise is. It was warm enough to be driving with my window down last night and right at 50 mph the noise started but I could hear it outside. I started running my hand around the sideview mirror and when I blocked right where it connects to the cab the noise went away. I'll try tightening the mirror down and see if that stops the vibration.

 

[jelag]

Harvey... . its a sprocket on the gear and the sensor is what's called a hall effect sensor..... a sensor that has no moving parts but as the sprocket(tooth) moves past the sensor... the metal in the sprocket changes the magnetic field in the sensor and than a signal is sent back to the computer...

You've got the principle nailed as to how it works... thought I'd add just a little.....