Usually, your vehicle’s onboard diagnostic system will throw a fault code whenever the ABS and the brake lights appear on the dashboard to tell you what’s happening with the brake system. But have you been in a moment where the ABS and brake decide to play hide and seek game—the lights appear on your dashboard, but there’s no logged error code on the onboard diagnostic memory to tell you what’s wrong with the system?
Do not worry. This article will explain the reasons for ABS and brake light on but no codes. You’ll also learn how to fix the brake and ABS lights on no code and how to reset the brake light and ABS light. Stay with me on this while I uncover all you need to know.
Causes of ABS and Brake Light on but No Codes
Intermittent sensor issues, problems with the ABS modules, low brake fluid levels, faulty brake pedal sensor, issues with the wheel speed sensor, worn brake pads, and lousy brake switch are the common reasons the ABS and brake light is on without registering any code.
Let me highlight these possible causes so you can see why and how they can cause the ABS and brake lights to pop on the dashboard without throwing any error code.
Faulty ABS module
The bad ABS module has provisions to throw error codes, it can sometimes fail without throwing any code.
The ABS module is a microprocessor that runs checks on the antilock braking system and processes the data from the hydraulic braking system and wheel speed sensors to know when to release braking power to prevent a wheel that is about to skid or locking up. However, the module can have internal issues that your vehicle’s onboard system may not detect immediately.
Malfunctioning brake light switch
A faulty brake light switch can also trigger the ABS and brake light on at the same time. The brake light switch is a small device attached to the brake pedal, and it is responsible for illuminating the brake lights when you depress the brake pedal.
In many modern cars, this tiny device does much more than that. It also works in harmony with the antilock braking system. If this switch malfunctions, it’ll affect the antilock braking system and cause ABS light on no code.
Weak or poor battery voltage
Another reason ABS lights are on without fault codes is weak or poor battery voltage. You may be wondering what relationship the battery and antilock braking system have. Believe it or not, if your battery is weak, it may not provide enough electric flow to the ABS, causing it to malfunction.
Lousy wheel speed sensors
A failing wheel speed sensor is another possible reason for the ABS light no code. The wheel speed sensor is a small device that detects the rotational speed of each wheel and supplies this information to the ABS and ESP control unit in the form of electrical signals. The ABS uses this electrical signal to determine if any wheel is locking up and prevent them from doing so.
If the wheel speed sensor malfunctions or fails, it will trigger the ABS and brake light on the dashboard, even though there’s nothing wrong with them. This may or may not throw a fault code. So, do not rule out lousy wheel sensors because your vehicle’s OBD system did not log any error code.
Also, the sensor can be in good condition, but a broken or damaged wire prevents it from communicating effectively with the antilock braking system.
Low brake fluids
In some cases, low hydraulic fluid in the braking system can cause the ABS and the brake light to appear on the dashboard. The brake fluid is the lifeblood of the braking system. Your hydraulic brakes will not function correctly without adequate fluid in the system.
Also, the ABS relies on the brake fluid to function effectively. If the brake fluid drops below the required level, a sensor in the master cylinder will trigger the ABS and brake light on the dashboard to notify the driver.
Worn brake pads
While not the common cause of ABS and brake lights, it can be the culprit. Worn brake pads will cause the brake fluid in the braking system to drop below a certain threshold. Doing this will indirectly cause the ABS and brake lights to appear on the dashboard. However, 80% of the time, worn brake pads are not the reason for the brake light on the dashboard.
Intermittent sensor problems
The most common reason for ABS light on no codes is intermittent sensor issues. This can happen when the wheel speed sensor, ABS, or related sensor experiences short-lived malfunctions but not consistently enough to log a fault code.
Failing sensors, loose connections, and damaged wirings are the possible causes of intermittent sensor problems.
Software malfunctions or electrical glitches
Software malfunction or electrical glitches with the ECM/PCM can cause the ABS light to appear on the dashboard. These glitches may not log any error code on the onboard car memory as they are often short-lived. This may be challenging to troubleshoot because the malfunctions may also cause other symptoms pointing to various things.
How to fix the ABS light on no code?
Since there are several reasons for ABS and brake lights to appear on the dashboard without throwing codes, there are several ways of rectifying it. Let’s look at these ways in the subsequent paragraphs.
Run a visual inspection
The first step to fixing this issue is to start by visually inspecting the components of the antilock braking system, such as the wirings, sensors, and connectors. Look for any sign of disconnection, deterioration, and damage. Addressing any physical issue could be all you need to fix the problem.
Top up the brake fluid
Open the brake fluid reservoir and check the level. If the brake fluid is below the normal range, top it with the recommended brake fluid for your vehicle. As explained earlier, low fluid levels can trigger the light, and topping it could be all you need to fix the underlying issues.
Check the brake pedal position sensor
Check the brake pedal position sensor and ensure it is working correctly. If it malfunctioning or damaged, replace it with a new one. Remember to recalibrate the new sensors for accurate readings.
Inspect the wheel sensors
Locate the wheel speed sensors and examine them for dirt, rust, and mechanical damage. Clean any dirt or debris from the sensor and its surroundings to enable them to provide accurate readings. Replace the wheel speed sensors if they are faulty.
Check the ABS module
Start by testing the antilock braking system power and ground to ensure it receives appropriate electric flow. Low or intermittent voltage drops will lead to issues with the antilock braking system. Check the ABS ground and power supply wires and ensure they supply adequate power.
After that, examine the wiring harness and ensure no signs of burnt, damaged, or frayed wires and loose connections. Repair or replace any damaged harness part and reconnect any loose connections. Scan the ABS for faults using an advanced onboard diagnostic scanning machine capable of ABS modules. Check and fix any error code stored in the ABS module, even if they are not logged on the car computer.
Run a function test on the antilock braking system components. Activate the individual wheel sensors or check the functionality of the ABS pump. This can help you identify problems yet to be logged as error codes. Finally, consult authorized service centers or your vehicle manufacturer to determine if there is any available software update for your antilock braking system. You can fix system glitches and malfunctions by updating the ABS software.
Is it safe to drive with ABS and brake lights on?
If ABS and brake lights come on simultaneously, your car is no longer safe to drive. It clearly indicates that there’s a problem with your brake system and that it is dangerous to continue driving with it.
This warning light shows the braking system malfunctioning, which could lead to a total break failure. Ignoring ABS light on but no fault codes could cause a collision, leading to injuries or loss of lives. Therefore, you should park your vehicle once the ABS and brake lights appear on the dashboard until you rectify them.
How do you reset the ABS and brake light?
Here are the simplified steps to reset your car’s ABS and brake light.
- Disconnect the positive battery terminal and depress and hold the brake pedal for a few minutes to drain the electric flow in the system.
- Reconnect the positive battery terminal. The brakes will be completely reset if the system has no underlying problem.
- If the warning light returns, you must replace the ABS sensor. Change the sensor and reset the system again, following the previous step.
- If the warning lights refuse to go away, diagnose the vehicle with an OBD2 scanner because the car still believes there’s an issue within the braking system.
To be precise, if you see the ABS and brake light on but no codes, an underlying issue needs to be addressed. Low brake fluid, faulty ABS module, faulty wheel speed sensor, and intermittent sensor problems are the most common reasons the ABS and brake light appear on the dash with no error codes.
This article has explained how to fix this problem in simplified steps. However, if you are not okay with this approach or do not trust your gut, have your mechanic troubleshoot and fix the problem.