Normal Operation

WARNING: This page is about a different car, the 2008 Ford RV Cutaway, 2008 Ford Econoline, 2008 Ford E450 Super Duty, and 2008 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

The front wheel speed sensors are "active" sensors and generate a square wave signal that is sent to the ABS module. When the ignition is turned to the RUN position, the ABS module carries out a self-test to determine if the sensors are functional. Voltage and ground are supplied to the front wheel speed sensors from the ABS module along a pair of wires.

The rear wheel speed information is sent to the ABS module from the PCM over the high-speed controller area network (HS-CAN) bus. The PCM receives the information from the transmission output shaft speed (OSS) sensor.

Wheel speed sensor DTCs will automatically clear when a successful test drive is carried out. A successful test drive should include speeds above 32 km/h (20 mph) for at least 3 minutes and at least one ABS stop.

DTC C1222 Wheel Speed Mismatch - When the vehicle speed exceeds 20 km/h (12 mph), if the ABS module detects a difference between wheel speed sensor signals, DTC C1222 will be set. DTC C1222 can also be set by damaged tone rings, mismatched wheel and/or tire sizes, driving the vehicle on one or more under inflated tires, an incorrect axle ratio in the PCM or the wrong axle being installed on the vehicle.

This pinpoint test is intended to diagnose the following:

Mismatched tire sizes
Wheel speed sensor ring
Wheel speed sensor
OSS sensor
OSS sensor tone ring
Incorrect PCM configuration
Incorrect rear axle
HS-CAN bus
ABS module