By: craig

craig — Wed, 26 Nov 2008 07:18:25 +0000

Hi Bob,
From the symptoms you are describing I believe the anti-lock braking system is being ‘triggered’ for some reason at these low speeds. A pulsating or vibrating pedal combined with a humming type brake noise is exactly what you would experience when the anti-lock system is triggered during an emergency stop.
Although I am not familiar with the Chevy Tahoe (I’m an Aussie) I believe that all anti-lock braking systems work on the same principle which is motion sensors attached to each wheel hub and when the vehicle is in motion and one wheel ‘locks up’ the control unit picks up that there is no signal from the stationary(brakes locked) wheel and responds by momentarily reducing the brake fluid pressure to that wheel, which gives you the pulsating brake pedal.
This leads me to think that there is a couple of possible scenario’s with your vehicle. Either one of the motion detector ‘rings’ on one of the hubs has come loose and is not turning at low speed, giving the control unit a false reading, one of the sensors that detect wheel movement may have been damaged at some stage as is not functioning correctly or there is a fault with the control unit itself.(Although usually in this case the warning light on the dash would illuminate)
As far as diagnosing the exact cause is concerned, the first thing I would be doing is removing each wheel and thoroughly checking the condition of the anti-lock ‘ring’ and sensor. You could also trace the wire from each sensor back to the control unit and check for any breaks or damage. Other than that there is not a lot you can do without the right equipment I’m sorry.
If you want to remove the wheels and inspect the sensor units yourself and have a digital camera I would be more than happy to take a look and see if we can spot anything amiss.
Sorry I can’t offer you more help than this.

By: bob

bob — Wed, 26 Nov 2008 02:15:32 +0000

I have 1998 chevy tahoe ,I recently started to have a problem with my anti lock brakes. At any giving moment when im slowing down to a stop (less than 3 miles an hr) or changing from drive to reverse or vice versa I experience my brake pedal pulsating , vibrating and or making a humming noise . I took the car to my mechanic and he told me that my brakes needed to be changed front and back and that i had a stuck calliper pin that just needed some lube to free it up but neither worked . The antilock braking system light is not on and I changed my rotors about 8 months ago .I need your advice cause i dont have the money to keep pumping into this vehicle on misdiagnosed fixes.

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By: craig

By: bob