If you’re a car owner, you’ve probably seen your ABS light turn on, and you may be wondering what it indicates, what caused it, and more importantly, is it okay to drive with it on?
In this article, I will answer all your questions about the ABS light so you’ll know everything you need to know!
What does the ABS Light mean?
If your ABS light is on, a problem has been detected in the anti-lock braking system (ABS). The Anti-lock Brake System means it helps prevent the vehicle wheels from locking during a brake. The ABS warning light is a warning that the anti-lock brake is not working properly.
When you either start the vehicle or turn on the ignition, the ABS light comes on for a second; during this time, the ABS is performing a self-check. After that, the light should be off.
If it hasn’t illuminated at all, the bulb may be burned out. If it is not turning off after the self-check or comes on while driving, then that would indicate that there is a problem and you will need to find out why.
Why ABS Is Important?
Takeaway: ABS will prevent the wheels from skidding and locking up while braking on slippery roads, thus giving shorter stopping distance and more steerage control.
If you lock up the wheels while braking (easily done on slippery surfaces), the tires lose most of their grip on the road and lengthen the stopping distance, and do severe damage to your ability to steer the car in a specific direction.
Before the invention of ABS, we taught students to pump the brakes if skidding, as pumping would allow the car to slow down a little with brakes on, and steer a little with brakes off. Essentially, that is what ABS is doing automatically to you, and it can do it much quicker.
Most automatic braking systems can also detect which wheels are locking up, and can typically modulate the braking force only to the locked-up wheels, creating an even higher control.
Why the ABS Light Could Be On?
Takeaway: Before you take your vehicle in, there are things you can likely do yourself that may solve the problem.
There are multiple parts to the ABS, and any of them can fail and turn on the warning light. You will probably need someone to plug in a special scanning tool to figure out where the problem lies, but there are some simple things you can probably do yourself before then.
If you discover anything wrong and you are able to correct it, you may take care of the problem.
The first thing is to check your tire pressures. If one of the tires is way low or high, the computer will get confused. Next check your brake fluid level in case it has gone low to normal wearing of the brakes (or maybe a leak).
Finally, check for a blown ABS fuse. If you have your owner’s manual, flip it to “Fuses” in the index and it should send you to a fuse block diagram and list.
Alternatively, you could Google “which fuse is for ABS on my (Year/Make/Model)?”, and you should find a similar diagram and list. Either way you can search the list of fuses for whatever applies to the ABS, and beware it might be more than one.
If you find one of these problems and are able to correct it, the ABS light will either go off on its own in a little while of driving, or you may be able to turn it off yourself.
Turning off the light can be anything from too simple (or easy) to rather complicated and mind-numbing. One way is to disconnect the battery for a while to reset the trouble codes. Even if you do, and you still have a problem, the light will come back on.
Causes of the ABS Light
#1. Bad Speed Sensor.
The wheel speed sensor tracks wheel movement and supplies the ECU with essential information for the functionality of the ABS.
If a wheel is logging more speed than the others, the ECU will put in more brake fluid to slow that wheel down for grip. When the wheel speed sensor fails, the ECU won’t get the information that it needs.
You will know the fault is there by noticing an ABS light showing up on your dash, but you will also notice that the car won’t even brake well, and may even start to lose traction when you hit the brakes.
The traction control light may also show up. The wheel speed sensor is mounted in close proximity to the wheel so that it can measure the speed of the wheel rotation.
Given the location near the brakes, the sensor can suffer excessive damage from heat, but it can also be damaged by debris or metal shavings that are from brake pad wear.
#2. Bad ABS Tone Ring.
The ABS sensor requires an ABS tone ring to read the wheel speed.
If the ABS ring gets rusty or cracks, it will return an incorrect measurement and your ABS light will be illuminated.
Some ABS rings are located inside the wheel bearing, requiring you to replace the whole wheel bearing. If it’s located on the driveshafts, however, you might be able to simply check and visually inspect it for cracks or other damage.
#3. Defective ABS Module or Wirings.
The ABS module can go bad, but it might be freshly corroded wiring causing the problem. Wires can corrode, causing delays or lack of communication, from the ABS module to the speed sensor.
It’s better to replace wiring rather than the ABS module, which is much more expensive if you’re unlucky.
Regardless of the problem, you should notice a lack of response from the brakes. The lack of response initially might only happen periodically, but will worsen until it’s noticed all the time. Or the brakes could lock up completely, or make clicking noises.
#4. Malfunctioning Hydraulic Pump.
The ABS system regulates the brake fluid that moves through the hydraulic pump, which in turn moves fluid through the brake cylinder so that each brake receives fluid when you press on the brake pedal.
The ABS will also modulate the brake pressure to each wheel based on the reading the speed sensor picks up, and it pumps the appropriate amount of fluid to the brakes in the areas where they needed it, in the correct amount.
The most of the time, it does what it was designed to do. If the hydraulic pump fails or develops a failure to the valve in the hydraulic system, the system will fail and cannot be used.
We don’t want either failure. The pump will run into contamination in the brake fluid such as debris and metal shavings, and will fail. It only helps a little if you change out the fluid regularly, but it prevents it as much as possible.
When the pump fails, the braking performance is affected. The brake performance will begin to reduce in performance and eventually perform less and less as time goes on.
If the master cylinder fails, the brake temperature could feel okay in that moment, and the next you could lose complete braking power. A very dangerous situation to be in.
You can also have a fluid leak in the defective part. If it were to leak fluid out of the defect, you could go from a firm feeling pedal to spongy feeling pedal to eventually the pedal sinking to the floor.
#5. Blown Fuse.
The ABS is controlled by the electrical components in your vehicle. The ABS has its own fuse. Fuses can fail. A fuse can blow for a number of reasons, or for no reason at all.
Fortunately, checking the fuse is an easy test. In fact, it may be the first test of your diagnostic process if you have no other symptoms other than the light on the dashboard.
#6. Low Brake Fluid.
The ABS pump relies on brake fluid to function properly. This fluid is pushed through the cylinder to service the brake system. You will encounter problems, perhaps an ABS light, if the brake fluid level becomes too low.
If the brake fluid level is low, it needs to be determined why. There could be a leaking brake fluid reservoir, air in the brake system, or a damaged seal.
It could also be an indication that your brakes are worn. If you allow the level to get too low, the ABS module is incapable of balancing brake pressure across each wheel and there will be slippage and skidding.
As the brake fluid level continues to decrease, you may experience difficulty stopping. It may also be that you hear more noise when braking.
Diagnose ABS Light
To figure out what needs to be replaced, consider the following;
- Check the ABS fuse. This is a super quick step that could save you a lot of trouble. It’s located in the fuse panel under the dash. Your owner’s manual should have a diagram as to where the fuse is located.
- Check the brake fluid level. If the brake fluid is low, fill it up. If it’s contaminated, drain it and refill it.
- Check the system for leaks. You should be able to see leaking brake fluid from underneath the car. Fresh fluid is a light-yellow color, whereas contaminated oil will be slightly darker, possibly brown.
- Test the ABS wheel sensor with the voltmeter. A good alternative is to read trouble codes with your OBD-II scanner, which should tell you if there is a fault.
If you still having trouble isolating the problem, you should bring the vehicle into a qualified mechanic to interrogate the system for further diagnostics.
How to Fix ABS Light
You can spend anywhere from $20 to $1,000 fixing the ABS light, depending on what’s causing the light to come on.
I’ll examine the most common repairs to fixing the ABS light, but you need to do a full diagnostic to determine what’s causing your problem before you start replacing parts. After all, there’s no need to put parts on the car that aren’t necessary.
The cheapest issue would be a blown fuse. Not only should this fix only cost you $20 or less, but it’s easy to fix. You simply need to open the fuse panel and swap out the one running the ABS.
If the brake fluid is low, the next easiest fix would be to add more brake fluid. This fix will only cost the price of the brake fluid, as long as there isn’t something causing the leak.
Now, you’ll need to replace a speed sensor or an ABS tone ring that are faulty. The average for this repair is probably somewhere between $100 and $300.
This seems to be one of the most common issues for the ABS light. You might also need to replace an ABS module or rewire it. To fix the wiring fault is probably cheaper, however a new ABS module will probably run $200 to $600.
Now we are at the larger of the problems, you will probably need to replace the hydraulic pump or a master cylinder. A new master cylinder could run from $300 to $600, and putting a new hydraulic pump on could run you $1,000 or more.
Can I Drive with the ABS Light On?
Short answer: Yes, but only if you know there’s a problem. Warning – the only time you should drive with the ABS light on is if you know for sure there are no issues. You obviously don’t want to have any issues with your normal braking, or you could be putting yourself in a dangerous situation.
The ABS system will be disabled if the ABS light is on and that could be dangerous if you’re not used to driving a vehicle without ABS.
Your braking system may feel normal but it could fail at any minute if there’s an underlying failure or problem. For that reason, it is important to take the ABS warning serious. You don’t want to be stuck anywhere and you don’t want to be involved in an accident.
I completely understand a budget and we know that car repairs never happen at a great time – financially.
However, if an accident had been caused, the price you pay could be immeasurable and it would be horrible to take that chance. Rather than take that chance, I suggest getting the ABS codes scanned to find out what the problem is.
How long can you drive with ABS light on?
You should not drive with ABS light on, especially if you don’t have experience driving vehicles without ABS.
However, if you are an experienced driver, you will still want to know why the light came on, you should get the car to a mechanic as soon as possible to diagnose the problem and make repairs.
Can low brake fluid cause ABS light to come on?
Yes. If the brake fluid is low enough, it is possible for the ABS pump to lose pressure and the ABS system would go into “fail-safe” mode and that is when the ABS light will come on.
Can you drive without ABS?
You can, but it is not recommended. Your stopping ability will be diminished without ABS and you will also have more difficulty controlling your vehicle under emergency conditions.
If you must drive without ABS, please be sure to give yourself more distance to stop, and again, be sure to be extra careful in slippery conditions.
Can a weak battery cause ABS problems?
A weak battery could cause ABS problems, but it is not very common. It’s more likely you will find other problems with the car before your battery issues. If you are having ABS issues, it might be worth checking the battery.