electric motor noise at idle

[rebelbayou]

Hi Everyone,

1998 4 Runner Limited with 3.4, auto. Just started noticing a small noise when coming to a stop and off and on when idling in gear. Actually sounds like a small servo motor. No vibration and cannot tell any difference in way engine runs. Goes away when I take off or accelerate. Turning AC off, radio off makes no difference, turning wheel makes no difference. Is there some kind of small electric motor or ABS pump or something that would cycle on and off under these condtions? Any advice or suggestons would be appreciated. Great forum, btw!

 

[morbidsanity]

mabey your alternator? thats what comes to mind, its sounds logical as when your motor runs it uses he power to recharge your battery....

 

[Riders of Lohan]

It's constant? or it turns on and off?

 

[rebelbayou]

It comes on from about 5 mph to a complete stop and seems to be the loudest about the moment the truck stops. Then it might seem to get a little louder for a second or two before it quits. Only hear it when coming to a complete stop. No other symptoms other than smalll whirring noise. Can't hear it when I take off.

 

[chimpy]

I think that noise is the ABS system doing a self check. My '01 does the same thing.

 

[rebelbayou]

That's kind of what I was thinking Chimpy. Didn't know for sure if the ABS is controlled by a small electric motor or what. The way the noise turns on and off leads me to believe it is going through some kind of check or test of some kind. ABS makes sense because it only does it when coming to a stop. Now off to find a manual to see where the ABS motor is and verify. Thanks for the reply.