ABS Brake System Questions, Operation And Description

An ABS warning light means a problem was detected in the anti-lock brake system. The computer system may need to be scanned for ABS codes. With the light on, ABS operation is disabled but normal braking in not effected.

Read some of our most common ABS Questions with answers from expert auto mechanics.

The operation of the antilock braking system (ABS) uses several different sensors, motors, and a computer in conjunction with the normal braking system of your car.

The Traction Control System is controlled by the ABS system and prevents wheel slip during acceleration.

The ABS regulates the brake pressure in order to reduce the chance of wheel lockup. Reduced wheel lock-up improve your control of the vehicle during braking on slippery pavement.

Improved stability and steering enable for greater control of the vehicle in the case of an abrupt stop. The ABS operation is available from approx. 3 mph to the maximum vehicle speed.

Why is my 1999 Pontiac Bonneville abs light on?

 Many things can cause this light on you car. A speed sensor, wiring to a sensor. Needs to have the computer scanned for codes first.

For some time my Abs light has been intermittent in coming on. Was advised to disconnect battery and leave it unhooked for at least one hour, then to re-connect but do not start the car for an hour. I have done this and the light has not come on again. Apparently has to do with allowing the cars computer(s) to totally shut down and then allowed to reboot before starting the car. This appears to have worked for me.

Thank ours has come on also we have a Chevy Uplander. I'm going to have my husband try this so that we can see if it works for us. We just had the back brakes done and now its coming on. Thank you for the tip.

 Disconnecting the battery is only temporary. With an intermittent problem, this will turn off the light, until the problem occurs again- then the light will be back on.

We just had our brakes checked and repaired and the ABS lights came on after that. Our mechanic said we could do our short trip and bring it in the following week. On the way home our van completely shut down and we were lucky enough to pull it off the road and not get hit by passing vehicles on a stormy snow day. Problem was a broken wire inside the casing hooked to the computer. A special machine had to be brought in to find the problems. $962.00 later we have a pink piece of wire that looks like it was burnt off of the computer. Can you see this happening on a busy 401 highway when you are in the middle of traffic? Shouldn't consumers be given some warning of these problems that may happen?.

 Have not personally seen a wire burned at the PCM. There is no telling what work has been done in the past on your vehicle that may have contributed to a wire burning. Maybe a mechanic did not route something correctly after a repair- say 2 years ago. You make it sound like this is a common problem and should have a recall, but it is not a common problem.

My 94 chevy Astro has a the antilock light on, and it had a check engine light. I check my oil and it was very low i put some oil and it when away but the anti lock stayed on what should i do in this case ??

 Now you need to get the codes scanned from the ABS computer to find out why the light is on the dash.

I have a abs light on, with right rear wheel locking on my 2000 Pontiac Sunfire.

 You could have the speed sensor for that wheel acting up, or a problem with the regular brakes, like a leaking wheel cylinder contaminating the shoes with brake fluid.

My ABS light is on and my brake pedal is extremely soft. I have to push it almost all the way down to get it to do anything. I have found that pumping the brake helps some, but still not comfortable with how the brakes are acting. I know I need to bring it in, and plan to. I am writing so someone can give me some kind of idea what might be the problem. I just do not want to go in blind and have someone try to tell me that I need all kinds of work that I dont actually need.

 A lot of this depends on what make, model and year is this car or truck. Could be a bad master cylinder, ABS pump, leaking line or wheel cylinder. ABS may not be related to the way the pedal is acting, could be a problem in the base brake system.

After start the engine my abs warning lamps goes off. After driving a short distance the ABS lamp comes on.

 The ABS light coming on when the car starts to move usually means a bad wheel speed sensor, since it senses wheel speed. If one reads 0 or different from the others, it turns on the light.

My ABS and Low TRAC light comes on while driving and when that happens the brakes sounds like it is grating and kind off slips before braking properly. It happens after I start my car, drive a little and then one comes on and then the other, I believe the low trac first and then the ABS. Can you advise why this happen and how soon I should get it fixed?

 Depends on what type of vehicle you are talking about. Could be a wheels speed sensor problem or a wiring problem at on of those sensors.

I have a Chevy 2005 Aveo hatchback and just yesterday the abs light came on and dont shut off what could this mean but the car dont feel any different it drives find like always?

 An ABS light would not affect the way your chevy Aveo runs. You need to scan computer codes. Possibly a wheel speed sensor.

I have a 92 Cadillac with only 12000 miles. The abs and traction off light stay on and cannot reset. The brakes are ok but are a little soft. Help?

 A problem in the ABS will also disable traction control. A scan is need to get the stored trouble codes.

I have a 2000 Chevrolet Malibu. I just had work done on the brake line and caliper on one side. After that the check engine light and ABS light came on. I'm getting tired of taking my car to my mechanic cause every other month or any time he works on it something else goes screwy with it. This car has less than 70k on it and the maintenance is always up-to-date. Good thing I'm getting a new car next month or I'd shoot my mechanic just on suspicion alone!!!

My Dad has a 2000 Mercury. ABS and Traction Light come on when he first starts the car and stays on. There are no codes on the computer which makes it difficult to diagnose. Any ideas?

 Are you sure you are scanning the ABS computer? If you are scanning the engine computer, there wont be ABS codes in there.

I have a 2004 Pontiac Grand Prix GTP supercharged I have a couple lights on but I have the abs, traction, stability and the service brake system. I know I need tire rods do you think all those light relate to that problem?

 Tie rods are not related at all. Read comments above.

I have a 2007 ford Edge the abs and tracking light is on, what could the problem be. It came on once before but went off.

 As with all the above posts, the ABS computer needs to be scanned for codes. Possible sensor or wiring.

I have a 2005 dodge grand caravan and my ABS light just came on. Can I continue to drive my vehicle.

 Yes you can still drive it. ABS light means a problem in ABS, not regular braking.

1999 Pontiac Grand Am with both the ABS, an Brake warning lights on my instrument panel. I replaced the low fluid sensor, the brakes are all new, and I read the codes. The codes are C1246, and C1286. Does this mean that I need a new Electronic valve that controls the rear brakes, installed, can I get one, or do I need to replace the whole motor control unit. I was hoping to get the valve, but is that possible. Does the Brake warning light come on to tell me that it is a rear valve problem? I checked the E brake switch and all is well. Give me some answers please. I have the mechanical experience to install any thing. Can I install a new rear control valve, or do I have to install a new unit?

 The code C1286 is caused by theC1246(Rear channel will not move). You may just have a loose nut that holds the rear channel gear on to the motor pack. Remove the lower cover on the motor pack and see if the center gear is loose or can spin freely.

I have a 2003 Buick Rendezvous and recently my anti-lock and AWD disabled light come on together. When I am driving straight it seems to be fine. But when I turn (left or right) and brake while turning both lights come on and it seems harder to stop. The light go off after driving straight for awhile or I turn the car off and do not come on again until I turn. Any ideal of what this could be?

 Warning light when turning the steering is usually caused by a partially broken wire in the harness that goes to one of the front wheel speed sensors- which is part of the hub bearing. Turning causes the harness to move and can cause an open circuit. A bad hub bearing can also do this, but usually a wire problem. Close inspection of the wires is needed.

I want to thank you for taking th time to respond to my above question on 3-10-11. Your answer was very helpful. I went to pick-n-pull, and removed a replacement motor pack from a 1999 pontiac Grand Prix that matched mine. It cost 60 dollars, and I had to cut the lines to the proportioning valve because they were steel fittings screwed into aluminum proportioning valve. I installed the unit into my Grand Am and had to use Vise Grip pliers to remove the lines to the pp Valve. I Bled the unit at the pp valve first, then at the solenoid valves, then at all the wheels like the manual says. All is well now. Problem solved. Thanks for all you do. Steve T.

 Thank you so much for the tip/donation Steve !

what tool am i to use to scan the ABS. Do i have to bring it into a dealership? Cant seem to find any part store that carries them. Thanks!

 If you cannot find the tool, you can go to any local repair shop, you do not HAVE to go to the Dealer.

I have a 99 Pontiac Grand Prix GT. My ABS light and trac off light is on continuously. I had it tested at my friends shop. And his Snap-ON tester gave me 2 codes. #1 is c0450 ans #2 is C0550. We could not locate them in his manuals. We are at a loss. Can you give me any ideals what they mean. Thanks in advance. Jamie

 C0450- Steering assist control actuator circuit.
C0550- ABS internal control module malfunction.

I have a 1988 BMW 635, the Anti-lock light started coming on and off about a week ago. When I am driving, the car seems to brake by it self every 10 to 15 seconds. It does not brake completely by it does slow the car down which also makes the automatic transmission shift down on gear. Do you what could be happening. Thank you.

i have a 2006 ford escape had front brakes done at the dealers 2 weeks later abs light comes on for one day then goes off for 3 days and comes on one more time for 10 min then off again i take it to the dealers they say its a speed sensor on the front wheel cost me 320 bucks.

Is an ABS Scan Tool different from a regular OBDII scan tool and if so, where do you plug it in??

 There are some cheaper scanners that are just for ABS, others scan the Engine computer, ABS, Airbag, etc all in one unit. They all plug into the OBDII connector under the dash.

Had the rear tires changed on 94 Lincoln Town Car yesterday and the anti-lock brake light came on, and stayed on, about a 30 minutes later. Could they have done something when replacing the tires?

 Yes, they may have damaged some wiring.

The Check Engine, Anti lock Brake, Trac Control, low tire pressure (has been on for a few days), and gas cap light came on yesterday. The gas cap light went off, but the others are still on. I just replaced the two front hub assemblies last month, and one rear was replaced 2 years ago under warranty. How should I proceed.

 You are going to have to have the ABS computer scanned for codes. Would also suggest the powertrain computer gets scanned, as the gas cap light does not always mean the cap is loose. That lights can come on with the check engine light for several reasons.

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