Possible Causes

Wiring, terminals or connectors
Tire pressure
Incorrect or mismatched tire
Wheel bearing
Wheel speed sensor encoder
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 COMPANY

Harness Side

Circuit

Fig 2: Left Front Wheel Speed Sensor Connector - C150

Courtesy of FORD MOTOR CO.

Harness Side

Circuit	Pin
LF WSS HI (Left Front Wheel Speed Sensor High) - VCA03	1 (VIOLET/WHITE)
LF WSS LO (Left Front Wheel Speed Sensor Low) - RCA17	2 (YELLOW)

Fig 3: Right Front Wheel Speed Sensor Connector - C160

Courtesy of FORD MOTOR CO.

Harness Side

Circuit	Pin
RF WSS HI (Right Front Wheel Speed Sensor HI) - VCA05	1 (GRAY/VIOLET)
RF WSS LO (Right Front Wheel Speed Sensor Low) - RCA19	2 (VIOLET)

Fig 4: Left Rear Wheel Speed Sensor Connector - C440

Courtesy of FORD MOTOR CO.

Harness Side

Circuit	Pin
LR WSS HI (Left Rear Wheel Speed Sensor High) - VCA04	1 (BLUE/ORANGE)
LR WSS LO (Left Rear Wheel Speed Sensor Low) - RCA18	2 (BROWN/GREEN)

Fig 5: Right Rear Wheel Speed Sensor Connector - C426

Courtesy of FORD MOTOR CO.

Harness Side

Circuit	Pin
RR WSS HI (Right Rear Wheel Speed Sensor High) - VCA06	1 (WHITE/ORANGE)
RR WSS LO (Right Rear Wheel Speed Sensor Low) - RCA20	2 (BROWN)

AB1: CHECK FOR ABS MODULE DTCS

Ignition ON, engine OFF.

Carry out the ABS self-test.

Is DTC C003x:29 or C003x:64 present?

Yes	No
Go to AB2.	For DTC C0031:07, C0034:07, C0037:07, C003A:07, C0031:2F, C0034:2F, C0037:2F or C003A:2F, Go to AB3. For DTC C0030:07, C0033:07, C0036:07 or C0039:07, Go to AB5.

AB2: 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 AB3.	INSTALL the correct size tire or wheel or ADJUST tire pressure as necessary. DRIVE the vehicle at a speed greater than 20 km/h (12 mph) to clear the ABS module wheel speed sensor DTCs.

AB3: CHECK THE WHEEL SPEED SENSOR MOUNTING

With the transmission in NEUTRAL, position the vehicle on a hoist. Refer to the appropriate Jacking And Lifting article.
Inspect the wheel speed sensor for correct installation and the fastener for looseness.
Is the wheel speed sensor installed correctly and the fastener tightened to specifications?

Yes	No
Go to AB5.	REINSTALL the wheel speed sensor and tighten the fastener to specifications. REFER to the appropriate procedure in the appropriate Anti-Lock Brake System (ABS) and Stability Control article. Go to AB4.

AB4: CHECK THE WHEEL SPEED SENSOR INPUTS

Ignition ON, engine OFF.
Access the ABS and monitor the LF_WSPD (SPD) PID.
Access the ABS and monitor the RF_WSPD (SPD) PID.
Access the ABS and monitor the LR_WSPD (SPD) PID.
Access the ABS and monitor the RR_WSPD (SPD) PID.
Drive the vehicle at a speed greater than 20 km/h (12 mph) while monitoring the PIDs.
Are the wheel speed PIDs within 5 km/h (3 mph) of each other and the vehicle speed as indicated on the speedometer?

Yes	No
The system is operating correctly at this time. The concern may have been caused by a loose or incorrectly installed wheel speed sensor. DRIVE the vehicle at a speed greater than 20 km/h (12 mph) to clear the ABS module wheel speed sensor DTCs.	Go to AB5.

AB5: CHECK THE WHEEL SPEED SENSOR FOR DAMAGE

Ignition OFF.
With the transmission in NEUTRAL, position the vehicle on a hoist. Refer to the appropriate Jacking And Lifting article.
Disconnect the suspect wheel speed sensor electrical connector.
Inspect the wheel speed sensor and harness for abrasions, broken connector tabs or water intrusion.
Is the wheel speed sensor and harness OK?

Yes	No
For Escape/Kuga with AWD, Go to AB9. For MKC with AWD, Go to AB9. For Ka, Go to AB8. For all others, Go to AB6.	INSTALL a new WSS. INSTALL a new wheel speed sensor. REFER to the appropriate procedure in the appropriate Anti-Lock Brake System (ABS) and Stability Control article. DRIVE the vehicle at a speed greater than 20 km/h (12 mph) to clear the ABS module wheel speed sensor DTCs.

AB6: CHECK WHEEL BEARING AND ENCODER FOR DAMAGE

Ignition OFF.
With the transmission in NEUTRAL, position the vehicle on a hoist. Refer to the appropriate Jacking And Lifting article.
Inspect the wheel bearings for abnormal wear or roughness and for deformation or contamination of the seal and encoder.
Is the wheel bearing and encoder OK?

Yes	No
Go to AB7.	INSTALL a new wheel bearing as necessary. REFER to the appropriate article. DRIVE the vehicle at a speed greater than 20 km/h (12 mph) to clear the ABS module wheel speed sensor DTCs.

AB7: CHECK THE WHEEL SPEED SENSOR PIDS

Ignition ON, engine OFF.
Access the ABS and monitor the LF_WSPD (SPD) PID.
Access the ABS and monitor the RF_WSPD (SPD) PID.
Access the ABS and monitor the LR_WSPD (SPD) PID.
Access the ABS and monitor the RR_WSPD (SPD) PID.
Drive the vehicle at a speed greater than 48 km/h (30 mph) while monitoring the PIDs.
Are the wheel speed PIDs within 5 km/h (3 mph) of each other and the vehicle speed as indicated on the speedometer?

Yes	No
Go to AB10.	CLEAN the space between the wheel speed sensor encoder ring and the wheel speed sensor. INSPECT the air gap. INSTALL a new wheel bearing or wheel speed sensor as necessary. REFER to the appropriate Suspension or Anti-Lock Brake System (ABS) and Stability Control article. DRIVE the vehicle at a speed greater than 20 km/h (12 mph) to clear the ABS module wheel speed sensor DTCs.

AB8: CHECK FRONT HALFSHAFT CV JOINT ENCODER AND REAR WHEEL BEARING ENCODER FOR DAMAGE

NOTE: It may be necessary to remove the rear wheel speed sensor or rear wheel bearing and wheel hub to thoroughly inspect the encoder.

Inspect the front halfshaft CV joint for damage, a torn boot, and for deformation or contamination of the wheel speed sensor encoder ring.
Inspect the rear wheel bearings for abnormal wear or roughness and for deformation or contamination of the seal and encoder.
Are the CV joints, wheel bearings and encoders OK?

Yes	No
Go to AB10.	INSTALL a new front wheel bearing and wheel hub assembly or rear halfshaft as necessary. REFER to the appropriate article. DRIVE the vehicle at a speed greater than 20 km/h (12 mph) to clear the ABS module wheel speed sensor DTCs.

AB9: CHECK REAR HALFSHAFT CV JOINT AND FRONT WHEEL BEARING AND ENCODER FOR DAMAGE

NOTE: It may be necessary to remove the rear wheel speed sensor or rear wheel bearing and wheel hub to thoroughly inspect the encoder.

Inspect the rear halfshaft CV joint for damage, a torn boot, and for deformation or contamination of the encoder.
Inspect the front wheel bearings for abnormal wear or roughness and for deformation or contamination of the seal and encoder.
Are the CV joints, wheel bearings and encoders OK?

Yes	No
Go to AB10.	INSTALL a new front wheel bearing and wheel hub assembly or rear halfshaft as necessary. REFER to the appropriate article. DRIVE the vehicle at a speed greater than 20 km/h (12 mph) to clear the ABS module wheel speed sensor DTCs.

AB10: CHECK FOR CORRECT ABS MODULE OUTPUT

Disconnect the suspect wheel speed sensor electrical connector.
Ignition ON, engine OFF.

Measure the voltage between:

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

Measure the voltage between:

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

Measure the voltage between:

(+) Left Rear Wheel Speed Sensor (C440) Connector, Harness Side	(-) Left Rear Wheel Speed Sensor (C440) Connector, Harness Side
LR WSS HI - VCA04 (BLUE/ORANGE) - Pin 1	LR WSS LO - RCA18 - Pin 2

Measure the voltage between:

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

Is the voltage greater than 10 volts?

Yes	No
INSTALL a new WSS. INSTALL a new wheel speed sensor. REFER to the appropriate procedure in the appropriate Anti-Lock Brake (ABS) and Stability Control article. DRIVE the vehicle at a speed greater than 20 km/h (12 mph) to clear the ABS module wheel speed sensor DTCs.	Go to AB11.

AB11: VERIFY ALL WIRING CONNECTIONS

Ignition OFF.
NOTE: The battery must be removed to access the ABS module electrical connector.
Remove the battery. Refer to the appropriate procedure in the appropriate Battery, Mounting and Cables article.
ABS Module connector disconnected. (C135)
Disconnect the suspect wheel speed electrical connector.
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 AB12.	REPAIR the connector or terminals. Refer to the appropriate Connector Repair Procedures Wiring Information, for schematic and connector information. DRIVE the vehicle at a speed greater than 20 km/h (12 mph) to clear the ABS module wheel speed sensor DTCs.

AB12: CHECK FOR APPLICABLE SERVICE ARTICLES

CHECK OASIS for any applicable service articles: TSB, GSB, SSM or FSA.
Do any applicable service articles exist?

Yes	No
DISCONTINUE this test and FOLLOW the service article instructions.	Go to AB14.

AB13: CHECK FOR CORRECT ABS MODULE OPERATION

Connect the suspect wheel speed sensor. Make sure it seats and latches correctly.
ABS Module connector connected. (C135) Make sure the connector seats and latches correctly.
Install the battery. Refer to the appropriate procedure in the appropriate Battery, Mounting and Cables article.
Operate the system and determine if the concern is still present.
Is the concern still present?

Yes	No
INSTALL a new ABS module. INSTALL a new ABS module. REFER to the appropriate Anti-Lock Brake System (ABS) and Stability Control article. 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. DRIVE the vehicle at a speed greater than 20 km/h (12 mph) to clear the ABS module wheel speed sensor DTCs.	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. DRIVE the vehicle at a speed greater than 20 km/h (12 mph) to clear the ABS module wheel speed sensor DTCs.

AB14: CHECK FOR CORRECT ABS OPERATION

Connect the suspect wheel speed sensor. Make sure it seats and latches correctly.
ABS Module connector connected. (C135) Make sure the connector seats and latches correctly.
Install the battery. Refer to the appropriate procedure in the appropriate Battery, Mounting and Cables article.
Operate the system and determine if the concern is still present.
Is the concern still present?

Yes	No
INSTALL a new HCU. INSTALL a new ABS module and HCU assembly. REFER to the appropriate Anti-Lock Brake System (ABS) and Stability Control article. ORDER a replacement ABS module and HCU assembly. INCLUDE the RVC form. If this is a Ford paid repair, INCLUDE the RVC on the warranty claim form. DRIVE the vehicle at a speed greater than 20 km/h (12 mph) to clear the ABS module wheel speed sensor DTCs.	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. DRIVE the vehicle at a speed greater than 20 km/h (12 mph) to clear the ABS module wheel speed sensor DTCs.

Yes

INSTALL a new HCU.
INSTALL a new ABS module and HCU assembly.
REFER to the appropriate Anti-Lock Brake System (ABS) and Stability Control article.
ORDER a replacement ABS module and HCU assembly. INCLUDE the RVC form.
If this is a Ford paid repair, INCLUDE the RVC on the warranty claim form.
DRIVE the vehicle at a speed greater than 20 km/h (12 mph) to clear the ABS module wheel speed sensor DTCs.

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.
DRIVE the vehicle at a speed greater than 20 km/h (12 mph) to clear the ABS module wheel speed sensor DTCs.