As you are all very well aware, occasionally anti-lock brake system (ABS) malfunctions can be very complicated and hard to diagnose. In the case of some late-model Ford truck anti-lock brake systems, however, several malfunctions may have a very simple solution.

Some 1997-1999 Ford Expedition, F-150, F-250 (2WD models only), or 1998-1999 Lincoln Navigator (2WD models only), can exhibit such diverse symptoms as: ABS lamp illumination, false ABS cycling at low speeds, increased brake pedal effort at low speeds, or any combination of the above. These problems all may be caused by an incorrectly installed front wheel speed sensor, a damaged wheel sensor, or a chipped or broken tooth on the tone ring resulting in reduced input to the ABS Electronic Control Unit (ECU). Refer to the following Service Procedure for details.

SERVICE PROCEDURE
1. If the ABS lamp is on, retrieve and record any diagnostic trouble codes.

NOTE: Usually codes C1145, C1148/1234, C1155, C1158/1233 or C1222, which are all related to a front wheel sensor malfunction, will be displayed.

2. Inspect both front sensor wires for tension due to improper routing (Figures 1 and 2). Make sure that the white clip, attached to sensor cable is properly located on protrusion of the upper control arm (Figure 1). Replace the sensor assembly if needed.

3. Carefully inspect the sensor wire at the sensor head. Look for any cracking or distress. Replace the sensor assembly if needed.

4. Inspect the tone ring for dents, flat spots, chips or other irregularities.

5. Inspect both front sensor bodies for improper seating to the spindle housing. The sensor bracket flange should be completely flush to the spindle housing (Figure 3). If any gap is present, replace the sensor assembly with a new front wheel speed sensor.

PARTS INFORMATION

• Front wheel Speed Sensor — (RH) XL3Z-2C204-BB.

• Front wheel Speed Sensor — (LH) XL3Z-2C205-AB.

If sensor replacement is required, all surfaces, including the hole where the sensor body is inserted, must be free of rust build-up. Use a wire brush to thoroughly clean all surfaces where the sensor seats. That’s all there is to it. Make certain that you clear any ABS codes that were displayed and test-drive the vehicle to confirm your repairs.

Written by ALLDATA Technical Editor, Rich Diegle. Rich is an Advanced Engine Performance Certified and ASE Master Technician with an Associate of Arts degree in automotive technology and 22 years of dealership and independent shop experience.

For additional information, visit www.alldata.com.