ABS and Traction Control Lights On Together: What to Check
Learn why ABS and traction control lights come on together, what to check first, and when a brake-system diagnosis is urgent.
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What the warning lights mean
The ABS light means the anti-lock braking system has detected a fault and may not prevent wheel lockup during hard braking. The traction-control light usually means traction control has been switched off because it cannot trust wheel-speed information. Your regular hydraulic brakes should still work, but braking and stability assistance may be reduced on slippery roads or in an emergency stop.
Check the brake warning light first
A red BRAKE warning light, a soft or sinking brake pedal, fluid leaking near a wheel, severe pulling, or grinding requires immediate attention. Stop driving and arrange a tow if any of those symptoms are present. An amber ABS light and traction-control light without other brake symptoms are usually less urgent, but schedule diagnosis soon and leave extra following distance.
How to check likely causes
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Step 1
Park on level ground, turn the vehicle off, and restart it once. Confirm whether both lights return immediately or only after driving. Note any recent battery replacement, jump-start, pothole impact, curb strike, brake work, wheel-bearing work, or tire change; each can point to the source.
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Step 2
Check brake-fluid level in the reservoir with the vehicle on level ground. Fluid below the MIN line can trigger brake-related warnings, but do not simply top it off without finding the reason. Worn brake pads, a leak, or a recently disturbed hydraulic system may be responsible.
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Step 3
Inspect the battery terminals for looseness or corrosion and consider battery and charging-system testing. Low voltage can set ABS and stability-control codes, especially after a weak start. Also check the owner’s manual for the ABS or electronic-brake-control fuse location; replace a fuse only with the same rating.
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Step 4
Look behind each wheel for a wheel-speed sensor harness that is loose, cut, rubbed through, or pulled from its connector. Front sensor wiring is commonly damaged by road debris, suspension movement, or corrosion. Do not crawl under a vehicle supported only by a jack.
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Step 5
Read ABS-capable diagnostic trouble codes with a scan tool. A basic engine-code reader may not access the ABS module. Codes identifying one wheel often indicate its sensor, wiring, connector, hub bearing, or magnetic encoder ring rather than the ABS module itself.
The most common repairs
A corroded connector or damaged wheel-speed sensor is a frequent repair, particularly in areas that use road salt. On many newer vehicles, the magnetic tone ring is built into the wheel bearing or hub assembly, so a bearing problem can create an intermittent sensor signal. A humming bearing, wheel play, or a warning that appears after 30 to 60 mph (50 to 100 km/h) supports that possibility. ABS module failures are less common and should be confirmed with professional testing before replacement.
When to book professional service
Book a brake or diagnostic inspection promptly if the lights stay on after a restart, return repeatedly, or appear with steering, stability-control, or speedometer problems. A shop can compare live wheel-speed data, load-test wiring, inspect hub encoder rings, and verify module power and ground. Depending on your state, warning lights may also affect a required safety or emissions inspection.
Check for recalls and known issues
If the warning started unexpectedly and your model has a known brake-system complaint pattern, check your VIN for open recalls through NHTSA; unbrokencar.com also offers a free VIN check. Recall repairs are generally performed by the manufacturer at no charge, while ordinary wear, wiring damage, and sensor failures are not normally covered.