Both the ABS and traction control lights turn on simultaneously because the 2 systems share the same control module and wheel speed sensors. A fault in any shared component triggers both warning lights at the same time.
What Do the ABS and Traction Control Lights Mean When They Come On Together?
NHTSA explains related safety context in NHTSA vehicle safety information.
The ABS (Anti-lock Braking System) light and traction control light indicate that 2 safety systems have been deactivated. The ABS prevents wheel lockup during hard braking. Traction control prevents wheel spin during acceleration. Both systems rely on shared hardware, so a single fault disables both.
These lights together do not always signal a major failure. They often point to 1 faulty component serving both systems.
Trailer ABS Wiring Diagram: Components, Configurations, and 4 Diagnostic Uses
Trailer ABS Blink Codes: How to Read Them and What 8 Common Codes Mean
Why Do the ABS and Traction Control Lights Turn On at the Same Time?
The ABS and traction control systems use the same wheel speed sensors and control module. Wheel speed sensors measure each wheel's rotation speed. This data feeds into a single control module. When the module detects an error, it deactivates both systems and illuminates both warning lights.
According to the National Highway Traffic Safety Administration (NHTSA), ABS and traction control have been standard in all new passenger vehicles sold in the United States since 2013.
What Are the 7 Common Causes of the ABS and Traction Control Light Turning On?
The ABS and traction control lights turn on due to 7 main causes:
- Faulty wheel speed sensor: A damaged or dirty sensor sends incorrect data to the control module.
- Defective ABS control module: A failed module disables both systems simultaneously.
- Low brake fluid: Fluid below the minimum level triggers both warning lights.
- Blown fuse: A blown fuse in the ABS circuit cuts power to both systems.
- Damaged wheel bearing: A worn bearing disrupts sensor accuracy, activating both lights.
- Faulty steering angle sensor: This sensor guides traction control. A fault triggers both lights.
- Wiring or electrical fault: Damaged wiring interrupts communication between sensors and the control module.
What Is a Wheel Speed Sensor and Why Does It Trigger Both Lights?
A wheel speed sensor is a magnetic sensor mounted near each wheel hub. It measures rotation speed and transmits data to the ABS control module. Vehicles use 4 wheel speed sensors, 1 at each wheel. A single faulty sensor is enough to trigger both the ABS and traction control warning lights.
How Does a Defective ABS Control Module Affect Traction Control?
A defective ABS control module stops processing wheel speed data. This causes both the ABS and traction control systems to shut down simultaneously. The module connects directly to the brake hydraulic unit and is located in the engine bay.
Is It Safe to Drive With the ABS and Traction Control Lights On?
Driving with both lights on is possible but not safe in all conditions. Standard braking remains functional. However, 2 critical safety systems are inactive:
- ABS will not prevent wheel lockup during emergency braking.
- Traction control will not prevent wheel spin on wet or icy roads.
The Insurance Institute for Highway Safety (IIHS) found that ABS reduces fatal crash risk by 18% in passenger vehicles. Without ABS, stopping distances increase significantly on wet and slippery surfaces.
Short drives to a repair facility are acceptable. Long-distance driving or driving in adverse weather with both lights active increases accident risk.
How Long Can You Drive With the ABS and Traction Control Light On?
Standard braking remains operational with both lights on. However, driving beyond 2 to 3 days without diagnosing the fault is not recommended. Emergency braking without ABS increases stopping distance and raises the risk of a collision.
How Do You Diagnose the ABS and Traction Control Warning Lights?
Diagnosing these warning lights requires an OBD-II scanner to retrieve stored fault codes. The process involves 4 steps:
- Insert the OBD-II scanner into the diagnostic port beneath the dashboard.
- Turn the ignition to the "on" position without starting the engine.
- Access the ABS fault code menu on the scanner.
- Match the fault code to the corresponding component using the scanner's database.
Common ABS fault codes and their meanings:
| Code | Meaning |
|---|---|
| C0035 | Left front wheel speed sensor fault |
| C0040 | Right front wheel speed sensor fault |
| C0045 | Left rear wheel speed sensor fault |
| C0050 | Right rear wheel speed sensor fault |
| C0110 | ABS motor circuit malfunction |
What Does an OBD-II Scanner Reveal About ABS Faults?
An OBD-II scanner displays alphanumeric fault codes. Codes beginning with "C" identify chassis system faults, including ABS and traction control issues. Many auto parts retailers, such as AutoZone and O'Reilly Auto Parts, offer free OBD-II scanning services.
How Do You Fix the ABS and Traction Control Light?
Fixing these lights depends on the fault code retrieved. There are 5 common repair methods:
- Replace the wheel speed sensor: Sensors cost $20 to $100. Labor adds $50 to $150.
- Top up or replace brake fluid: Full replacement costs $70 to $120 at a repair shop.
- Replace the ABS control module: Total cost ranges from $300 to $800 including labor.
- Replace the blown fuse: Fuses cost under $5. The fuse location is listed in the owner's manual.
- Repair damaged wiring: Wiring repairs cost $100 to $400 depending on damage extent.
How Much Does It Cost to Fix the ABS and Traction Control Light?
Repair costs for ABS and traction control lights range from $5 to $800 depending on the faulty component.
| Cause | Parts Cost | Labor Cost | Total |
|---|---|---|---|
| Wheel speed sensor | $20 to $100 | $50 to $150 | $70 to $250 |
| Brake fluid replacement | $10 to $30 | $30 to $80 | $40 to $110 |
| ABS control module | $150 to $500 | $100 to $300 | $250 to $800 |
| Fuse replacement | $1 to $5 | $0 to $50 | $1 to $55 |
| Wiring repair | $20 to $100 | $80 to $300 | $100 to $400 |
Can a Faulty ABS Module Cause the Traction Control Light to Turn On?
Yes. A faulty ABS module causes the traction control light to turn on. Both systems depend on the same module to process wheel speed data. When the module fails, the traction control system loses its data input and deactivates. Both warning lights illuminate as a result.
Replacing the ABS module restores both systems. In most modern vehicles, a new module requires professional programming to match the vehicle identification number (VIN).
Jimmy O’Riley is a UK-based mobile mechanic and automotive diagnostic specialist operating out of Bedfordshire, England. He founded O’Rileys Autos in 2011 with a focus on bringing professional vehicle repairs directly to customers at their homes and workplaces.
With over a decade of hands-on experience, Jimmy specializes in ABS diagnostics, brake system repairs, diesel emissions faults, and DPF cleaning. He is recognized across the UK and Ireland as one of the leading specialists in vehicle braking and emissions systems, earning the title “The DPF King” from his growing online audience.
Jimmy documents real-world automotive repairs through his YouTube channel, which has accumulated over 97,000 subscribers and nearly 2,000 published repair videos. His content covers ABS fault diagnosis, wheel speed sensor testing, brake module replacement, and roadside repair procedures across a wide range of vehicle makes and models.
He is active on YouTube, Instagram, and Facebook under O’Rileys Autos.