Huge clunk when using hill descent control

[SuperGreg]

Yesterday I was in stop and go traffic on a steep hill and decided to try the hill descent control for the first time to see how it worked. I pressed the button and let the car do its thing. It made some grinding noises and then a very loud clunk from the front end. It rolled forward another few feet and another very loud clunk. I pressed the button to turn it off, and I still got two more loud clunks rolling forward before it stopped.

Everything seems normal now, but I'm wondering what in the world was clunking? I'm afraid to try the feature again.

Any ideas?

 

[Odrapnew]

I've only used that 1 or 2 times to try it out. I can't remember the exact sounds, but I remember it being more of a 'boing' sound.
Not sure what the clunking would be....maybe the brakes cycling on/off?

 

[ExPlat]

The last sharp clunk sound from under the drivers floorboard of my Exp was just before my PTU destroyed itself. I don't like it when the car does that.

 

[SuperGreg]

Yeah I don't know if it could be the brakes... I didn't feel any difference in the vehicle speed just a very loud clunk. Did not sound good at all! The descent control just modulates the brakes right? I'm not sure what else could be activated to cause the clunk.

 

[peterk9]

I believe traction control is involved along with the anti-lock brakes.

Peter

 

[Adrian Gitch]

I've used it once in the mountains and dont recall any part of the drivetrain clunking. Like Peter said, the feature controls the brakes, traction control and shift of the transmission so you only have to focus on steering. Maybe the anit-lock brake system?