1. Scan for ABS Diagnostic Trouble Codes (DTCs)

• Use an OBD‑II scanner to read ABS-related DTCs (e.g., C0021–C0024 for wheel speed sensors) 

• These codes pinpoint whether the issue stems from sensors, the ABS module, or wiring.

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2. Check Brake Fluid Level & Quality

• Low or dirty fluid can trigger the ABS light—top off or flush if fluid is dark or below the minimum mark 

• Consistently low fluid may indicate a leak.

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3. Inspect & Clean Wheel Speed Sensors

• Check sensors near the rotors for dirt, corrosion, or damage. Clean with a soft brush or electrical cleaner 

• You can test sensor output with a multimeter

• “99% sure it’s a bad wheel speed sensor… You won’t have ABS when slamming on the brakes… spend $30… easy fix.”

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4. Examine Tone Rings

• The tone ring works with the sensor to track wheel speed. Rust or damage alters the sensor gap, causing misreads 

• Clean or replace if necessary.

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5. Check ABS Fuse & Wiring

• A blown ABS fuse is a common issue—check and replace with the correct amperage 

• Inspect wiring harnesses for damage or corrosion—intermittent ABS lights can signal wiring faults 

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6. Test ABS Module & Pump

• Internal faults in the module or pump can cause ABS failures. Professionals can perform hydraulic and electrical module tests 

• A pulsating pedal even on dry roads may point to a faulty ABS valve 

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7. Verify Battery & Electrical Health

• Low voltage or poor ground can falsely trigger ABS faults. Ensure the battery and alternator are working properly .

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8. Road-Test & Monitor ABS Light Behavior

• After fixes, drive on a safe road to test ABS. The light should go off; pedal should pulse under braking only when needed .

• If the light persists after DIY steps, take the vehicle for professional ABS diagnosis