2003 Rear Wheel ABS Late To Engage?

[s5uewf]

I have a 2003 Avalanche and several times now
on rainy pavement or on sandy pavement my
rear wheels have locked up when braking, sending
the truck slightly sideways.

I have ABS, but it does not engage in these
situations. If I afterwards stomp on
the brakes, the ABS does work, however
only after the rear wheels lock up.

This seems to be counter to the entire premise
of having ABS brakes...

Is anyone else noticing their rear wheels
lock up - or that their ABS is slow to kick in?

Can ABS sensitivity be adjusted?

Emery

 

[BBlueAV]

Doesn't sound right to me. I have a similar rig and have never had that happen, even is slushy conditions. I'd take it in to the dealer and have them check it out!! In reality, even with ABS, the wheels do lock, albeit momentarily. The system then senses this and releases pressure, unlocking the wheels. (To see this in action, slam on your brakes in an empty parking lot and stop. If you look at the area where you travelled while stopping, there will be a slight skip-skidmark that is barely visible from the correct angle of light. This is rubber from where the wheels were frozen momentarily. It is faint and will literally blow away within a short period of time.) If your feeling the rear-end slide with a lock-up, it sounds like the system is not proportioning correctly. The AV should have a proportioning valve...maybe another member can say more about it...so I don't want to point totally in that direction.

Good luck!