Normal Operation and Fault Conditions

The wheel speed sensor uses the tone ring to generate a square wave signal proportional to wheel speed which is sent to the ABS module. The front wheel bearing, rear axle shafts, tone rings and wheel speed sensors must be undamaged and free from any contamination to produce a clean signal for use by the ABS module. Also, all 4 tires and wheels must be of the same manufacturer recommended size for the wheel speed sensor to generate an accurate wheel speed signal. 

Possible Causes 

• Tire Pressure
• Incorrect or mismatched tire
• Wiring, terminals or connectors
• Wheel bearing
• Wheel speed sensor tone ring
• Wheel speed sensor
• ABS module
  NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may cause damage to the connector.

Fig 1: Antilock Braking System (ABS) Module Connector - C135

Courtesy of FORD MOTOR CO.

Fig 2: Left Front Wheel Speed Sensor Connector - C150

Courtesy of FORD MOTOR CO.

Fig 3: Right Front Wheel Speed Sensor Connector - C160

Courtesy of FORD MOTOR CO.

Fig 4: Left Rear Wheel Speed Sensor Connector - C440

Courtesy of FORD MOTOR CO.

Fig 5: Right Rear Wheel Speed Sensor Connector - C426

Courtesy of FORD MOTOR CO.

1. B1: CHECK FOR ABS MODULE DTCS 
   • Ignition ON, engine OFF.
   • Carry out the ABS self-test.
   • Is DTC C003x:01, C003x:11, C003x:12 or C003x:14 present? 

     Yes	No
     For DTC C0031:01, C0031:11, C0031:12, C0031:14, C0032:11, C0034:01, C0034:11, C0034:12, C0034:14 or C0035:11, Go to PINPOINT TEST M . For DTC C0037:01, C0037:11, C0037:12, C0037:14, C0038:11, C003A:01, C003A:11, C003A:12, C003A:14 or C003B:11, Go to PINPOINT TEST N .	Go to  B2.

2. B2: CHECK THE TIRES SIZE AND PRESSURE 
   • Ignition OFF.
   • Verify all the tires and wheels are the same size and the tire size and inflation pressures are correct as indicated on the VC label.
   • Are the tires and wheels OK? 

     Yes	No
     Go to  B3.	INSTALL the correct size tire or wheel or ADJUST tire pressure as necessary.

3. B3: CHECK THE WHEEL SPEED SENSOR AND ELECTRICAL CONNECTOR 
   • With the transmission in NEUTRAL, position the vehicle on a hoist. Refer to JACKING AND LIFTING .
   • Disconnect the suspect wheel speed sensor electrical connector.
   • Using a good light source, inspect the wheel speed sensor and electrical connector for the following:
     • corrosion - install new connector or terminal and clean the module pins
     • damaged or bent pins - install new terminals or pins
     • pushed-out pins - install new pins as necessary
     • spread terminals - install new terminals as necessary
     • water intrusion - clean and dry the connector, install a new connector as necessary
   • Inspect the wheel speed sensor and harness for abrasions, broken connector tabs or water intrusion.
   • Are the wheel speed sensor and harness OK? 

     Yes	No
     Go to  B4.	INSTALL a new wheel speed sensor for the one in question. REFER to the appropriate procedure in ANTI-LOCK BRAKE SYSTEM (ABS) AND STABILITY CONTROL .

4. B4: INSPECT THE WHEEL SPEED SENSOR MOUNTING 
   • Inspect the suspect wheel speed sensor and fastener for looseness.
   • Inspect the suspect wheel speed sensor installation.
   • Is the wheel speed sensor installed correctly and is the wheel speed sensor fastener tight? 

     Yes	No
     Go to  B5.	REINSTALL or TIGHTEN the wheel speed sensor fastener to specification.

5. B5: CHECK THE FRONT WHEEL BEARINGS AND REAR ENCODERS FOR DAMAGE 
   • Inspect the suspect front wheel bearing for abnormal wear or roughness and for deformation or contamination of the seal and wheel speed encoder ring.
   • Inspect the suspect rear wheel bearing for abnormal wear or roughness and for deformation or contamination of the seal and wheel speed encoder ring.
   • Are the wheel bearings and encoders OK? 

     Yes	No
     Go to  B7.	For the front wheel hub, INSTALL a new wheel hub as necessary. REFER to the appropriate procedure in FRONT SUSPENSION SYSTEM . For the rear wheel bearing or rear encoder, INSTALL a new wheel bearing or encoder as necessary. REFER to the appropriate procedure in REAR DRIVE AXLE/DIFFERENTIAL .

6. B6: CHECK THE FRONT WHEEL BEARINGS AND REAR ENCODERS FOR DAMAGE 
   • Inspect the suspect front wheel bearing for abnormal wear or roughness and for deformation or contamination of the seal and wheel speed encoder ring.
     NOTE: It may be necessary to remove the rear axle shaft to thoroughly inspect the rear wheel speed encoder.
   • Inspect the suspect rear wheel speed sensor encoder for signs of damage, deformation and missing teeth.
   • Are the wheel bearings and encoders OK? 

     Yes	No
     Go to  B7.	For the front wheel speed encoder ring, INSTALL a new wheel hub as necessary. REFER to the appropriate procedure in FRONT SUSPENSION SYSTEM . For the rear wheel speed encoder ring, INSTALL a new encoder ring as necessary. REFER to ANTI-LOCK BRAKE SYSTEM (ABS) AND STABILITY CONTROL .

7. B7: CHECK THE WHEEL SPEED SENSOR CIRCUITS FOR AN OPEN 
   • Ignition OFF.
   • ABS Module connector disconnected. (C135)
   • Measure the circuits between the ABS module and the suspect wheel speed sensor.
   • Measure the resistance between:

     (+) ABS Module (C135) Connector, Harness Side	(-) Left Front Wheel Speed Sensor Sensor (C150) Connector, Harness Side
     LF WSS HI - VCA03 (VIOLET/WHITE) - Pin 9	LF WSS HI - VCA03 - Pin 1
     LF WSS LO - RCA17 (YELLOW) - Pin 8	LF WSS LO - RCA17 - Pin 2

   • Measure the resistance between:

     (+) ABS Module (C135) Connector, Harness Side	(-) Right Front Wheel Speed Sensor (C160) Connector, Harness Side
     RF WSS HI - VCA05 (GRAY/VIOLET) - Pin 5	RF WSS HI - VCA05 - Pin 1
     RF WSS LO - RCA19 (VIOLET) - Pin 4	RF WSS LO - RCA19 - Pin 2

   • Measure the resistance between:

     (+) ABS Module (C135) Connector, Harness Side	(-) Left Rear Wheel Speed Sensor (C440) Connector, Harness Side
     LR WSS HI - VCA04 (BLUE/ORANGE) - Pin 7	LR WSS HI - VCA04 - Pin 1
     LR WSS LO - RCA18 (BROWN/GREEN) - Pin 6	LR WSS LO - RCA18 - Pin 2

   • Measure the resistance between:

     (+) ABS Module (C135) Connector, Harness Side	(-) Right Rear Wheel Speed Sensor (C426) Connector, Harness Side
     RR WSS HI - VCA06 (WHITE/ORANGE) - Pin 11	RR WSS HI - VCA06 - Pin 1
     RR WSS LO - RCA20 (BROWN) - Pin 10	RR WSS LO - RCA20 - Pin 2

   • Is the resistance less than 3 ohms? 

     Yes	No
     Go to  B8.	REPAIR the open circuit.

8. B8: CHECK FOR RETURNING DTCS 
   • ABS Module connector connected. (C135)
   • Connect the suspect wheel speed sensor electrical connector.
   • Ignition ON, engine OFF.
   • Clear the ABS DTCs.
   • Test drive the vehicle under normal driving conditions above 20 km/h (12 mph).
   • Carry out the ABS self-test.
   • Is one or more of the DTCs shown in the DTC Fault Trigger Conditions table present? 

     Yes	No
     Go to  B9.	The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues.

9. B9: VERIFY ALL WIRING CONNECTIONS 
   • Ignition OFF.
   • ABS Module connector disconnected. (C135)
   • Disconnect the suspect wheel speed sensor electrical connector.
   • Disconnect all in-line electrical connectors between the ABS module and the suspect wheel speed sensor.
   • Using a good light source, inspect all disconnected electrical connectors for the following:
     • corrosion - install new connector or terminal and clean the module pins
     • damaged or bent pins - install new terminals or pins
     • pushed-out pins - install new pins as necessary
     • spread terminals - install new terminals as necessary
   • Are the connectors free of corrosion, damaged pins, bent pins, pushed-out pins and spread terminals? 

     Yes	No
     Go to  B10.	REPAIR the affected connectors or terminals. REFER to OEM CONNECTOR REPAIR PROCEDURES for schematic and connector information.

10. B10: CHECK FOR CORRECT ABS MODULE OPERATION 
    • ABS Module connector connected. (C135) Make sure the connector seats and latches correctly.
    • Connect the suspect wheel speed sensor electrical connector.
      • Make sure the connector seats and latches correctly.
    • Connect all in-line electrical connectors between the ABS module and the suspect wheel speed sensor.
      • Make sure the connectors seat and latch correctly.
    • Operate the system and determine if the concern is still present.
    • Is the concern still present? 

      Yes

      No

      INSTALL a new ABS module. CHECK OASIS for any applicable Technical Service Bulletins TSBs. If a TSB exists for this concern, DISCONTINUE this test and FOLLOW the TSB instructions. If no TSBs address this concern, INSTALL a new ABS module. REFER to ANTI-LOCK BRAKE SYSTEM (ABS) AND STABILITY CONTROL . ORDER a replacement ABS module and INCLUDE the RVC on the form. If this is a Ford paid repair, INCLUDE the RVC on the warranty claim form. When complete, SELECT the "X" in the top right corner to CLOSE this procedure and RETURN to the PTS web site.

      The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues. If this is a Ford paid repair, INCLUDE the RVC on the warranty claim form. When complete, SELECT the "X" in the top right corner to CLOSE this procedure and RETURN to the PTS web site.