Seeing the ABS light on at the same time your speedometer stops working is more than just annoying—it can be a real safety concern. If the speedometer is dead, you can’t accurately judge your speed (which affects safe driving and can easily lead to speeding tickets). And if the ABS warning is lit, you also can’t be sure your anti-lock braking system will step in correctly during hard braking on wet or slippery roads.
The good news is that these two symptoms often share a common cause. In many vehicles, the speedometer doesn’t get speed information directly from the transmission—it gets a vehicle speed signal through the ABS system (wheel speed sensors and the ABS module). When that signal drops out, the ABS light comes on and the speedometer may go to zero. Our guide below covers the most likely causes and the best “fix-first” solutions in the order technicians typically diagnose them. You’ll also find answers to common questions in the FAQ section.
Possible Solution #1: Replace a Malfunction ABS Sensor
A malfunctioning ABS sensor is one of the most common triggers of the ABS light on and speedometer not working. On a 4-channel ABS setup, you’ll typically find a wheel speed sensor at each wheel hub/knuckle area (near the rotor/hub). On some rear-wheel-drive (RWD) vehicles, the speed sensor may instead be located at the rear differential, depending on design. These sensors monitor wheel rotation speed and send a signal to the ABS control module.
The ABS module uses that wheel speed data to prevent wheel lock during braking by rapidly pulsing brake pressure. If one sensor fails or provides an implausible reading, the system flags a fault and turns the ABS light on to indicate the ABS may be disabled. Depending on your vehicle’s network design, this can also disable or affect traction control, stability control, cruise control—and in many vehicles, it can cause the speedometer to stop working because the speedometer relies on the same vehicle-speed data stream.
To fix the problem, you’ll need to replace the faulty sensor (or repair what’s causing the sensor to report incorrectly). ABS sensor replacement is generally straightforward for a technician and often takes about 30–60 minutes with the proper tools. However, don’t overlook the simplest possibility: sometimes the sensor itself is fine but is covered in debris or the tone ring/reluctor is contaminated. In that case, cleaning the sensor area and checking for damage can restore proper operation without replacement. A specialist can tell the difference by scanning the vehicle and comparing live wheel speed data from all corners.
Expert tip: A scan tool that shows live wheel speed is the fastest way to identify the faulty corner. The bad sensor is often the one reading “0 mph” while the others read normally, or the one showing an unstable or wildly different value at low speed.
Possible Solution #2: Fix Wiring Issues
If the ABS sensor itself isn’t the problem, the next suspect is the wiring. The wiring connecting a speed sensor (in the transmission or differential on some vehicles) to the control unit or instrument cluster can become damaged. Likewise, the wiring from the ABS sensor to the ABS control module can also fail due to corrosion, road salt exposure, age, vibration, or physical damage (especially near the wheel where the harness flexes constantly).
When wiring is compromised, signal transmission becomes unreliable or stops completely. The ABS module then loses speed input, triggers the ABS warning light, and the speedometer may drop out because the speed signal is missing. Also, wires can short or a fuse can blow. While it’s less common for both the ABS system and speedometer to have independent wiring failures at the same time, it’s very common for one wiring fault (especially ABS sensor wiring) to disrupt both systems.
You need to identify wiring faults and repair them properly. If there’s a blown fuse, replace it—but also look for the reason it blew (shorted harness, damaged connector, water intrusion). Simply replacing a fuse without finding the cause may lead to repeated failure.
Expert tip: Pay close attention to harness routing at the wheel wells. It’s common for wiring to rub through where it clips to the suspension or where it’s stretched during steering and suspension movement.
Possible Solution #3: Fix a Computer Malfunction
Your engine control module (ECM) is the engine’s brain and is involved in many calculations, including vehicle-speed-related logic. More importantly, modern vehicles rely on multiple modules sharing information on the data network (CAN bus). If a module “hangs,” glitches, or communication breaks down, you can see odd symptoms such as an erratic or dead speedometer along with warning lights.
While the ABS system is typically controlled by a dedicated ABS module, the ECM and ABS module share data. If the ECM is faulty or communication is disrupted, the ABS light may illuminate due to miscommunication or missing data. In some cases, resetting the ECU/network can help if the issue is software-related. A common DIY reset method is disconnecting the battery’s negative terminal for at least 15 minutes.
Important note: Disconnecting the battery can reset learned values and may erase radio presets or clock settings. Use this reset as a troubleshooting step—not as a replacement for proper diagnosis.
Sometimes the reset won’t help. If a control module is failing internally, it may require professional testing, repair, or replacement. Leave that task to a qualified technician, especially because many modules require programming/coding after replacement.
Possible Solution #4: Faulty ABS Module
A faulty ABS module can absolutely cause the ABS light to come on—and it can also affect the speedometer if your vehicle uses the ABS module as the source of the vehicle speed signal. When the ABS module fails (electronically or hydraulically), the system may disable ABS operation and flag a warning. In vehicles where the speedometer depends on the ABS module’s speed calculation, the speedometer may drop out too.
Fixing a failed ABS module requires accurate diagnosis. A professional will typically scan for ABS-specific trouble codes, check power/ground and network communication, confirm sensor inputs, and then determine whether the module is defective. Some ABS modules can be rebuilt; others require replacement and programming. This is not the place for guesswork, because module replacement can be expensive and may not solve the issue if the true problem is a sensor, wiring, or tone ring fault.
Possible Solution #5: Low Brake Fluid
The ABS may malfunction if brake fluid is too low. Low fluid can introduce air into the braking system, reduce hydraulic pressure stability, and cause the ABS to disable itself and turn on a warning light. Since ABS relies on hydraulic braking performance, low fluid levels can compromise how the system operates, and your vehicle may display ABS warnings as a result.
The solution is to top up the brake fluid. This is one of the most straightforward DIY maintenance tasks, but it must be done correctly.
Open the hood and locate the brake fluid reservoir. You’ll usually find it on the master cylinder, near one of the rear corners of the engine bay (commonly on the driver’s side in many vehicles). Open the reservoir cap and slowly pour brake fluid using a funnel. Ensure the fluid level sits near the “MAX” or high marking.
Replace the cap, close the hood, and drive the car carefully to see whether the brakes feel normal and whether the warning light clears. If low brake fluid was the root cause, topping it up may resolve the ABS light. And if the ABS speed signal was the cause of the speedometer failure in your specific vehicle, restoring the ABS system can also restore the speedometer.
Expert caution: Brake fluid doesn’t “disappear” for no reason. Low fluid often indicates worn brake pads (fluid level drops as caliper pistons extend) or a leak. If the level drops again, inspect for leaks immediately.
Possible Solution #6: Replace Worn out Brake Pads/Rotors
The ABS light can illuminate when the braking system has issues such as severely worn brake pads or rotors—especially if wear leads to abnormal sensor gap, damaged tone ring/reluctor, or poor wheel speed signal consistency. While ABS is primarily monitoring wheel speed signals, brake condition still matters because mechanical brake problems can contribute to irregular braking behavior or sensor-related issues.
So, ensure your brakes are in good condition. Driving with worn pads/rotors is dangerous. It increases stopping distance and the risk of an accident. If brake components are worn to the point of metal-to-metal contact, you can also damage rotors and potentially create additional repairs.
Expert tip: If your brake fluid is low and your pads are thin, replacing pads may restore fluid level naturally (after proper caliper piston retraction). Always confirm brake system health as part of ABS diagnosis.
FAQs
How Can You Accurately Diagnose a Problem in Your Car?
To accurately diagnose a problem and apply the correct fix, get yourself a bi-directional scanner. This type of tool can read ABS trouble codes (not just engine codes), view live data like wheel speed sensor readings, and in some vehicles run actuator tests. When a warning light turns on, the stored DTCs can point you directly to the affected wheel sensor, circuit, or module.
For example, ABS codes can tell you whether the issue is a specific wheel speed sensor, a sensor circuit, a module internal fault, or communication/power problems. That diagnostic clarity saves money because it reduces parts-swapping.
How Much Does Fixing a Speedometer Cost?
Fixing a speedometer can cost anywhere between $100 and $400, depending on the extent of the damage, your car model, and your location. Basic repairs (such as fixing a wiring problem) may cost roughly $100. On average, many owners pay about $250, but costs can increase if the cause is an ABS module or instrument cluster issue.
Conclusion
As discussed, an ABS light combined with a dead speedometer can result from several issues—most commonly a faulty wheel speed sensor, wiring faults, or (less often) an ABS module or module communication problem. In many vehicles, the speedometer depends on ABS wheel speed data, which is why a problem affecting ABS may also be the reason your speedometer stopped reading.
A good DTC code scanner—especially one that can access ABS modules—can help you diagnose the problem accurately and fix it faster. And if DIY repair feels challenging, there’s no shame in using a reliable mechanic. ABS and braking systems are safety-critical, and professional diagnosis is often the smartest investment when symptoms involve braking control and speed feedback.
