DAC: Shuddering/clattering noise?

[Martinjmpr]

I've never had a vehicle with DAC before and last month when I was on the Alpine Loop, I thought I'd try it on a steep downhill. Well, it made such a godawful clattering, shuddering noise, I quickly switched it off and just modulated the brake like I did on my 3rd gen.

Just last week after washing and waxing, I thought I'd give the DAC a try on a flat street, just to see if it did the same thing. Well, it did.

Is it supposed to do that? Everything else in the 4wd system seems to work fine (and I used 2wd/4wd, High and Low, both locked and unlocked center diff on that trip to make sure it did.)

If the DAC is broken or inop, that's not a big deal, I don't see that I really need it anyway. I never had any issues with my '99 even descending Red Cone or Schofield Pass, both very scary, steep downhill slopes. Given that the 4th gen has superior brakes (disks in the rear vs. my 99's drums), I should be fine without the DAC, but my concern of course is that a problem with the DAC could indicate some kind of malfunction in the T-case or the ABS (doesn't the DAC just modulate the brakes kind of like the ABS system does?)

Thanks in advance for any advice.

 

[CXS]

Yes, it's supposed to do that.

 

[marked]

It's working right. I'll probably never use it unless I somehow end up going down a steep very slippery slope - just working the brakes myself feels a whole lot better.

 

[JB.]

I've never had a vehicle with DAC before and last month when I was on the Alpine Loop, I thought I'd try it on a steep downhill. Well, it made such a godawful clattering, shuddering noise, I quickly switched it off and just modulated the brake like I did on my 3rd gen.

Just last week after washing and waxing, I thought I'd give the DAC a try on a flat street, just to see if it did the same thing. Well, it did.

Is it supposed to do that? Everything else in the 4wd system seems to work fine (and I used 2wd/4wd, High and Low, both locked and unlocked center diff on that trip to make sure it did.)

If the DAC is broken or inop, that's not a big deal, I don't see that I really need it anyway. I never had any issues with my '99 even descending Red Cone or Schofield Pass, both very scary, steep downhill slopes. Given that the 4th gen has superior brakes (disks in the rear vs. my 99's drums), I should be fine without the DAC, but my concern of course is that a problem with the DAC could indicate some kind of malfunction in the T-case or the ABS (doesn't the DAC just modulate the brakes kind of like the ABS system does?)

Thanks in advance for any advice.

Yep, the god awful racket is normal.

The target speed of 2-4mph (closer to 4 when it gets steep) limits the usefulness. Good thing you didn't try it out on something like the rocks of Schofield. When my 4runner was new, I used it at the steps on Black Bear. It was too fast, of course, and I got lucky I didn't sustain any damage. Previous to that I had used it on Red Cone because I was pretty new to offroading and was under the influence of the excessive caution put forth in the Colorado 4wd books about the danger of the descent. It made that a breeze, of course, but the open nature of that hill made it feel like I was crawling more slowly than I really was, thus my brilliant idea to use it on Black Bear.

It's a nice tool to have access to for just the right circumstances, but those are rare.