Abs and brake light issue

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Rocket Man

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What scanner are you using? If you’re getting a light, there’s a code.
 

Jakespeed63

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Sorry for not writing down the DTC, but when I scanned this 2011 5.3l Tahoe, the code was relative to the fluid level sensor, in the master cylinder reservoir.
As part of the brake service, for this customer, I flushed the system and removed the sensor for inspection(Autozone wanted $95 for a new one) After installing the old sensor and topping off the fluid level, the lights did not reappear. Both red brake light and yellow Stabilitrak lights would illuminate in the morning. Today it worked fine. Going to call this one fixed. Got off easy, compared to some of you.

JT
 

pumpkin_hook

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Your ABS fuse may have been removed because the ABS may have been activating randomly. Mine was doing this (00 Tahoe) so I removed the fuse. Turned out to be a bad Hub wire.

The fuse was pulled initially, I replaced and removed it until I replaced the front hubs (SKF) complete with sensors. Initially the fault did not go away. A different scan tool captured it was the left rear that was causing the error. I ordered new rear sensors but have yet to install them as I have not had traction/abs faults in two weeks. Is there a re-learn process? Moving onto the next project - air bag sensors.
 

PNWYukon

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Condition

Some customers may comment on ABS activation at low speeds, usually below 8 km/h (5 mph). Upon investigation, the technician will find no DTCs set.

Cause

The cause of this condition may be an increased air gap between the wheel speed sensor and the hub reluctor ring due to rust and debris built up on the sensor mounting surface.

Correction

Measure AC voltage and clean the wheel speed sensor mounting surfaces.

1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in the General Information sub-section of the Service Manual.
2. Disconnect both the front wheel speed sensor connectors at the frame and harness.
3. Place a Digital Volt Meter (DVM) across the terminals of each wheel speed sensor connector.
4. Rotate the wheel clockwise approximately one revolution per second. The minimum reading should be at least 350 ACmV's. If the reading is less than 350 ACmV's, remove the wheel speed sensor. Refer to the applicable Wheel Speed Sensor Replacement procedure in the ABS sub-section of the Service Manual.
5. Plug the wheel speed sensor bore in order to prevent debris from falling into the hub during service.
6. Clean the wheel speed sensor mounting surface using a wire brush, sand paper, emery cloth, scotch brite, or other suitable material. Be sure to thoroughly clean the wheel speed sensor surface. There should be no rust or corrosion.
7. Check the sensor head to determine if it has been warped/distorted due to the corrosion build up or other causes. Check the mounting surface on the sensor head for flatness by placing it on the edge of a metal machinists scale or other suitable straight edge to measure the flatness. Check the sensor for flatness in multiple (minimum 3) positions/directions. If the sensor head is distorted, replace the sensor.
8. Apply (spray) two thin coats of the specified rust penetrating lubricant (corrosion inhibitor) to the complete sensor mounting surface on the bearing hub. Allow to dry for 3-5 minutes between coats. Use ONLY Rust Penetrating Lubricant, P/N 89022217 (in Canada, P/N 89022218).
9. When the corrosion inhibitor is dry to the touch (about 10 minutes), apply a thin layer of bearing grease to the hub surface and sensor O-ring prior to sensor installation. Use ONLY Wheel Bearing Lubricant, P/N 01051344 (in Canada, P/N 993037).
10. Install either the original sensor or a new one in the hub. Ensure that the sensor is seated flush against the hub. Refer to the applicable Wheel Speed Sensor Replacement procedure in the ABS sub-section of the Service Manual.
11. Place the DVM across the sensor terminals and recheck the voltage while rotating the wheel. The voltage should now read at least 350 ACmV's.
 

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