Anti-lock braking System (ABS)
June 15, 2006 by Alborz Fallah
Anti-lock braking System (ABS)
Anti-lock braking system prevents your car’s brakes from “locking up” and skidding. When the brake pedal is hit with force, short sharp pulsations are felt as the car’s computer system applies and release braking effort. A typical ABS is composed of a central electronic unit (CEU), four speed sensors covering all wheels, and two or more hydraulic valves connected to the brake circuit. The CEU continiously monitors the rotation speed of each wheel to determine if wheels are going to lockup. It can detect this by sensing wheels which are rotating considerably slower than the others. Once it has detected a possible lockup – the CEU moves the valves to help relieve the pressure within the braking circuit, by doing so it helps to reduce the braking force on the targetted wheel. Following that the wheel then turns faster and when it starts turning too fast, the force is reapplied. The ABS system does the prococess repeatedly.
Problems with ABS
The sensors on the wheels might get contaminated by metallic dust. When this condition occurs the sensors become less efficient in picking up problems. In modern ABS systems, two more sensors are added to help:
- wheel angle sensor,
- gyroscopic sensor
The idea behind this is that when the gyroscopic sensor detects that the car’s direction is not the same as what the wheel sensor reports, the ABS software will cut in to brake the necessary wheel in order to help the car go the direction the driver intends.
For more information on how ABS works, click here
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I have a 2007 Corolla LE with major brake problems that TOYOTA service cannot figure out.
R U Ready?!!!
FIRST TIME:
When I was on the highway the brake system (ABS?) comes on without braking. Smoked…..stunk. It felt as though I had the emergency brake on. And then it would go away after I stopped and turned the car off.
I took the car into our dealership where they could not find a problem after testing.
SECOND TIME:
I took the assistant service manager for a test drive where it happened again just as the first time. And I had a witness!!
They replaced the pads, calipers, and rotors and returned my car to my home the next day.
THIRD TIME:
That very next day, when going to work, it happened again not two miles down the road!! Called the assistant service manager and he came to see for himself. He drove the car back to the dealership with the brake stuck and again they replaced the pads, the calipers and rotors.
FOURTH TIME:
FYI I live in Winona MN on the southeastern side of the state.
I went on a business trip to northcentral Minnesota. About a five hour trip.
My return trip (from hell)on a Friday,….. IT HAPPENED AGAIN. I had to be towed to the nearest Toyota dealership. In Minneapolis. Toyota provided a loaner to use until repaired.
The dealership in Minneapolis could not find any brake problems just as they could not find with the dealership in Winona.
I told them I could not drive this car. That I need a reliable car commuting to and from work daily 100 miles.
Well,…..I get my car back tomorrow (Saturday) eight days from the dreaded tow to Minneapolis.
I will pursue the LEMON LAW.
OK!!!
Your turn.
Advice?
Tim Gantenbein
215 Washington Street
Winona, Minnesota
55987
non comment
Maybe Tim should get a job closer to home
Tim- The ABS indicator light came on in June ‘07- took it to the dealer. They gave me a loaner car (’07 Camry) until the required fix (New ECU Module)came in.
It came in 5-1/2 weeks later. Apparently, it’s a chronic problem in ‘07 Corolla’s with ABS and it requires newly programmed ECU’s to fix.
When I finally picked it up, the Service Manager said he had four more Corolla’s waiting for the same thing.
Dale Melton
dalemelt@mail.com
hi