The likely reason your ABS light is on after replacing rotors and brakes on your 2004 Chevy Colorado is that:
* The sensor is dirty or damaged: During brake work, the ABS sensor can easily be bumped, scratched, or have debris interfere with its operation. The sensor itself is fragile and needs a clean, unobstructed path to the reluctor ring (the toothed ring on the wheel hub that the sensor reads).
* The sensor is misaligned: The sensor needs to be precisely positioned to read the reluctor ring. Even a slight misalignment can disrupt the signal.
* The reluctor ring is damaged: While less likely after *only* rotor replacement, the reluctor ring could have been damaged. This is far more likely if the hub was removed.
* Wiring issue: A wire connecting the sensor could be damaged or loose.
Therefore, you don't reset the sensor; you troubleshoot the potential causes:
1. Inspect the sensor: Carefully examine the ABS sensor for any damage, dirt, or debris. Clean it with brake cleaner and a soft brush (never use metal), paying close attention to the sensing face. Ensure the mounting is secure.
2. Check for proper alignment: Make sure the sensor is correctly aligned with the reluctor ring. Refer to your service manual for the precise gap specification (if any).
3. Inspect the reluctor ring: Carefully check the reluctor ring for damage, bent teeth, or corrosion. Replace the ring if it's damaged.
4. Check the wiring: Examine the wiring harness for any damage, breaks, or loose connections. Repair or replace as needed.
5. Clear the ABS code (if necessary): After addressing the above points, you may need to clear any ABS codes stored in the vehicle's computer. This usually requires an OBD-II scanner with ABS capabilities. Many auto parts stores will scan your car for free. *Do this only after completing the previous steps.* Simply clearing the code without fixing the underlying issue will likely result in the light returning.
Important: If you're uncomfortable performing these checks, take your vehicle to a qualified mechanic. Improperly diagnosing and repairing ABS systems can be dangerous. A faulty ABS system can significantly impair your ability to brake effectively in emergencies.
