ABS Failures

Are you aware that the majority of ABS problems are from loose wheel bearings? When diagnosing an ABS failure warning and you have a sensor failure code, first check for loose wheel bearings before replacing the sensor. In most of these cases ABS failure warnings arise after brake shoe replacement and during reinstallation of the drum. Either the sensor gets bumped, pushing it out too far from the tone ring, or the bearings are not tightened to specifications. Loose bearings allow the wheel to move just enough to push the sensor out of range of the tone ring.

To avoid this and also premature bearing failure, always follow the proper procedures found in your MCI maintenance manual. Also include the following steps:

  1. Re-adjust the ABS sensor to verify it is positioned properly. After the hub is re-installed and the bearing pre-load is set, push the sensor in toward the tone ring until the sensor touches the ring (The retainer clip for the sensor will establish the proper gap to the tone ring.)
  2. Most importantly, BE SAFE. Always practice safe shop practices whenever doing any maintenance on your coach.


Motor Coach Industries - An NFI Group Inc Company: Corporate Address 200 East Oakton Street, Des Plaines, Illinois 60018 | Phone: 866-MCICOACH

Copyright 2004-2020 Motor Coach Industries Int'l, Inc. and its subsidiaries. All Rights Reserved.