Electric motor noise?

[ColoradoSilverado]

I have this noise that sounds like a electric motor running, at first I thought it was the ABS pump but it's not. I hear it with the engine running while driving or standing still, sometimes it goes off for a while but it's on like 90% of the time. I crawled under the truck and it almost sounds like it's coming from the transfer case. Any thoughts?

[MT-2500]

Does 4W shift from 2W to 4W and back?
If noise from transfer case unplug it and see if noise quits.
And feel ABS motor for motor runnning.

[ColoradoSilverado]

Originally Posted by MT-2500

Does 4W shift from 2W to 4W and back?
If noise from transfer case unplug it and see if noise quits.
And feel ABS motor for motor runnning.

4WD selector works fine (drove thru the snow today and shifted from Auto 4WD to 4WD several times). ABS pump I unplugged (both electrical connectors) and it still makes the noise. I also unplugged the plug to the transfer case which also made no difference.

Bert

[MT-2500]

Originally Posted by ColoradoSilverado

4WD selector works fine (drove thru the snow today and shifted from Auto 4WD to 4WD several times). ABS pump I unplugged (both electrical connectors) and it still makes the noise. I also unplugged the plug to the transfer case which also made no difference.

Bert

Noise sometimes travels .
Go over everything and see if you can feel or hear where it is coming from.
Sometimes a long steel bar or pipe or listening device helps find it.
Also sometimes fuel pump can make extra noise.
Good Luck

[mustanger999]

Your power steering pump could be the source for the noise. If fluid is too low or if pump is going out it can make a whining noise much like an electric motor. Does the noise increase when you turn the steering wheel?

[ColoradoSilverado]

I will definitely let you guys know what I find but it's gonna have to wait a few days, it's to cold and too much snow right now.

Bert

[ColoradoSilverado]

Well, still haven't been able to figure out what the noise is, it's definatly coming from the transfer case, weird thing is that it always sounds the same, standing still idling or driving down the road, switching between 2WD, 4WD and AWD doesn't make any difference, sometimes it will stop for a few seconds and then it's back again. Any thoughts?

Bert

[MT-2500]

Unplug the transfer case shift motor and see if noise leaves.
Also sometimes ABS brake motors make same noise.

[ColoradoSilverado]

Forgot to mention, noise is only when engine is warmed up. Will try the transfer case plug later today when it's a little warmer outside.

Bert

[semisendiz]

Well, here is something for you, but this WAS my noise: Radio has a cooling fan, starts on and off, when truck warms, pull it out radio (or just disconnect when sound comes on) to see if this is it. It was in mine.
Good luck.

[ColoradoSilverado]

This is what I eliminated so far: ABS pump, Power Steering Pump and Transfer case.

Bert