Thread: Antilock Brake Problem

I have a problem when its wet outside that everytime I hit the brakes the Antilock Kicks in and it makes the antilock noise.... It never did it b4 but ever since summer its been doin it.... Any ideas? It would be most appericated....

Thanks

Provided there is no issue with the computer in the ABS controller, ABS only comes on when the tires slip "too much." Tire slip ratio is the ratio of the speed the tire would be spinning if it was perfectly round and synced with vehicle speed and what speed it is actually rotating at. Unless you hear tire squeel, the tire slip ratio is between 1% and ~5%. When the brake is locked and the tire does not spin, the tire slip ratio is 100%. Depending on the tire, you get the most traction between ~10% and ~20% slip ratio.

ABS will always activate if the brake locks. To optimize stopping distance, the controller will also use ABS to prevent the tire from slipping too much. To understand too much, think about tire traction for acceleration. If the tire spins too much (lots of tire slip, noise and smoke), then you get beat off the line. If you can get it to just start to squeel, the tires will "hook" and the car will launch well. The ABS controller tries to keep the tire in its sweet spot by stopping you braking hard enough to lock the tire. The ABS controller is optomized to work with the factory tire and brake system, but it still works well with most tires and brakes that you put on the car. The ABS controller is tuned to work on wet surfaces, ice and snow, although a non-ABS car will stop better on snow or gravel because you want to lock your tires and let the snow pile up in front of the tire.

If the car's tires and brakes are stock, it's likely that either your tires are bald (less than 2/32nds tread depth), the calipers are frozen and don't retract properly, or the controller is bad. Tread depth is easy to determine, and if you change your brakes you'll find out if the caliper is frozen. If all of that checks out and you still have a problem, it may be your controller.

If you have non-stock tires or brakes, they could be the issue. If your brakes perform much much better than stock, the you could be overwhelming your tires too easily. If your tires perform a lot better than stock, the controller can be mis-tuned. It is also possible that your tires have really bad wet traction. I have a similar problem, in that my GXP comes with summer tires. They aren't meant to work below 40 degrees or on snow. I would get ABS coming on if I didn't drive like my grandmother, and turning a corner always activated stability control. I switched to winter tires (Dunlop Graspics, 225/55R17 with new 17" wheels all around) and now the car feels stuck to the ground again. I can't accelerate like I could on the stock 255/45R18s in the summer, but it's a small price to pay to keep my car on the road. Long story short, if you have performance tires on your car, you are trading wet/snow/ice traction for dry traction. It's not a bad trade if you know what you are doing.

Did you ever fiqure it out? My 06 does the say thing. I had new tires put on last year and it just started doing it this winter. I had the passenger side hub replaced, was wondering if it could be a speed sensor in the other?

If the ABS light is on, you really need to start by scanning for trouble codes. That will narrow it down for you.