Auto manufacturers equip vehicles with safety features to keep drivers and other road users safe. One of these safety features is the anti-lock braking system (ABS). The Anti Lock Braking System regulates your car in heavy braking situations.
Any time you do any brake system maintenance or repair, such as replacing calipers, master cylinders, wheel pistons, or hoses in your brake system, air can get trapped in the brake circuit. The problem is the trapped air is compressible.
So, whenever you press the brake pedal, the air inside the brake circuit must be compressed before the hydraulic fluid. This will cause a spongy, soft feeling when depressing the brake pedal. Plus, the stopping distance will increase.
You have to bleed the ABS module with a scan tool to remove the trapped air. I understand that not everybody can afford a scan tool. So, in this article, I’ll show you how to bleed ABS without a scan tool and how to know when the ABS needs bleeding.
What is an Anti-lock Braking System (ABS)?
Before knowing how to bleed ABS brakes, let’s find out what is an ABS and why we need one.
ABS or an Anti-Lock Braking System is a piece of safety equipment that prevents the wheels of a vehicle from locking up under emergency, panic, or harsh braking conditions and helps them maintain grip on the road.
There are four major components of a typical anti-lock braking system:
- Speed sensors – They keep track of how fast the wheel or wheels are rotating.
- Valves – Valves in the brake line allow, block, and release pressure on the brakes by assuming three different positions.
- Pump – These pumps are filled with hydraulic fluid and apply pressure to the brake drums or calipers on demand.
- Controller – The electronic control unit (ECU) is the brain of the ABS and uses data from the sensors to determine whether to pump the brakes or not.
How do I know if my ABS module needs to bleed?
First of all, we have to know the meaning and purpose of an ABS. ABS is the abbreviation of Anti-locking Braking System. This electronic device system processes the signal from the ABS sensors.
It then sends this signal to the powertrain control module (PCM). The PCM uses this information to create electronic information that ensures the system works as predefined by the car manufacturer.
In other words, the ABS module is a microprocessor that analyzes data or runs a diagnostic test on the hydraulic braking system and the wheel speed sensors to know when to release braking pressure to any wheel that is about to skid or lock up.
The most common symptom of air in ABS module is a spongy brake pedal. The reason is that the trapped air in the system must be compressed before the pressure applies to the brakes. Bleeding the brake system is all you need to address the underlying issues.
Other symptoms that indicate the ABS needs bleeding include;
- The illumination of the ABS warning light
- The appearance of the ESP warning light
- The ABS may activate even when it is not needed. The brake pedal may suddenly vibrate and jerk.
- A lousy ABS module or one that needs bleeding will throw error code U0121.
Can you Bleed an ABS system without a scan tool?
You can bleed your ABS without a scan tool if your vehicle has ABS module bleeder screws.
However, you should bleed the ABS with a scan tool if you need a more straightforward process. You can search for ABS scan tool rentals to rent the tool from your neighborhood.
How to bleed ABS module without scan tool Step By Step
Bleeding ABS brakes is more challenging than the process of bleeding the brake system because the ABS module has a lot of chambers and moving parts in it. Most ABS modules do have bleeding valves but usually, these are not enough to take all the air out.
While it is time-consuming work for a DIY-er, the process is not too complicated. Here are the steps of how to bleed air from ABS module. Follow the instructions below and you will know how to bleed ABS brakes without scan tool.
Things you will need
Bleeding the ABS module is not so difficult to do. But it might take some time because you need to bleed each wheel separately. If wonder how to bleed ABS module without scan tool, here are the tools you need.
- Car jack
- Turkey baster
- Drip pan
- Brake fluid
- Tubing
- Hammer
- Lug wrench
- Car Stands
Step 1 – Getting ready
First, you will need to park the car on a flat level with good lighting and ventilation conditions. Engage the parking gear to make sure that the emergency brakes are applied.
Step 2 – Removing the wheels
Using the car jack, lift the car to a comfortable level so that you can remove the four wheels comfortably so that you can reach the bleeders easily.
Step 3 – Drain the brake fluid
The brake fluid resolve is placed under the hood of your car. It is a small transparent container with metal tubes connecting to each wheel. These are the so-called brake lines.
When you have located the reservoir, empty the old brake fluid completely and refill it with a new one. Make sure that you get the right fluid for your car by asking your trusted mechanic before buying.
Step 4 – Locate the brake bleeder screw
The next step of how to bleed the ABS module without a scan tool is reaching the bleeding port in the brake caliper.
Use the correct bleeder wrench to loosen the bleeder screw, remove the dust cap and take the vacuum hose, tubing and put one end of it in an empty plastic bottle and the other end attached to the bleeder screw.
Take someone with you as a helping hand to pump the brake continuously until all the fluid has been drained into the bottle. Once done with all the wheels, you can confirm if the brake fluid reservoir is indeed empty.
Step 5 – Tighten the bleeder screw and refill the cylinder
Just before returning the bleeder screw, ask your friend to press the brake pedal down and hold it there.
Open the bleeder screw to let trapped air get out and tell him to keep holding the pedal until you are sure that the bleeder screw is tight as it was before. You have to repeat this process several times to ensure no air bubbles are left in the brake lines.
Keep in mind that you have to do this for all the wheels, and it must be in the following order: Right rear, left rear, right front, left front.
The bleeding process varies depending on the model of the vehicle or the ABS system that you have. The steps we mentioned should work for most generic ABS.
After that, open the master cylinder and refill it with new brake fluid until it reaches the full level.
Make sure that when you are draining the brake fluid, keep checking the fluid levels on the master cylinder so as not to drain the cylinder and let air get into the system.
Step 6 – Check for the leaks
After bleeding all the brake lines, tell your friend to pump the pedal and you walk around the vehicle to check if there are any leaks because of pumping. During this, your friend should ensure the pedal goes up and down to the recommended levels.
Step 7 – Put the parts back together
The last step of how to bleed the ABS module without a scan tool is to refit all the wheels back and be ready to test your brakes.
Take a test drive to see if the brakes are working right. Also, remember to clean the area as you might have let the residue liquid pour around. Safety first!
How do you bleed the ABS module with the scan tool?
If your ABS module is not equipped with a bleeder, you have to use a scan tool to perform proper bleeding instead of manually activating ABS pump.
Using Autel Scanner Maxi Check Pro will make the job very easy and save much time. But if you can’t afford the tool, you can try one of the cheapest ABS bleed scan tools on Amazon.
Connect a scan tool to the OBD11 port under the steering wheel. It will communicate with the ABS module and activates the pump. Then, follow the prompt to cycle the ABS solenoids to bleed out air.
FAQs.
Q: Can I drive with a bad ABS module?
Yes, you can drive with a bad ABS module. However, the ABS warning light on the dashboard means you should take caution while driving the vehicle.
While you don’t necessarily have to stop the vehicle, some ABS functions will stop working. For instance, the ABS module will not send braking pressure to any wheel about to skid or lock up.
Q: How much does it cost to fix the ABS module?
The cost of fixing a lousy ABS module depends on factors like your vehicle make and model, location, and the technician fixing the vehicle.
However, the average cost for ABS module replacement ranges from 340$ to 1,100$. The exact price for your car can be higher or lower than this.
Q: How long should an ABS module last?
The longevity of an ABS module depends on your maintenance culture and driving habits. Under perfect conditions, ABS modules can last as long as ten years or 100,000 miles. But it may fail much earlier if you don’t maintain it properly.
Maintaining proper fluid levels and doing a scheduled brake fluid flush will extend the lifespan of the ABS module.
q: Is it safe to remove the ABS fuse?
Yes and No. If you remove the ABS fuse, the brakes will still work, but you’ll miss some braking features, such as the ABS module preventing the wheels from skidding or locking up.
However, if you need full control of the wheel when racing or want to skid the wheels, removing the ABS fuse is safe.
Q: Can a bad ABS module cause transmission problems?
Yes, the ABS can affect transmission performance. In some vehicles, the transmission control module collects data from the wheel sensors or ABS for optimal performance.
If the ABS module becomes faulty, it will send a false or no reading to the transmission control module. This will invariably cause transmission problems like delayed shifting, hard gear shifting, limp mode, and poor to jerky gear shifts.
Final Words
When you finish bleeding the ABS module and the whole brake circuit, you must ensure everything is in place, and there is no leak. Ask the helper to continuously press the brake pedal to detect if there’s anything wrong.
This is the most simplified guide on how to bleed the ABS module without a scan tool you’ll find anyway. It’s easy and safe. But if you don’t trust your gut or don’t know the working principle of your brake system, contact a professional mechanic.