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) and at least one ABS stop.

DTC C1233 LF Wheel Speed Input Signal Missing - When the vehicle speed exceeds 20 km/h (12 mph), if the ABS module does not receive a signal from the LF wheel speed sensor, DTC C1233 will be set. This DTC can also be set by an excessive wheel speed sensor-to-tone ring air gap or a damaged tone ring.
DTC C1234 RF Wheel Speed Input Signal Missing - When the vehicle speed exceeds 20 km/h (12 mph), if the ABS module does not receive a signal from the RF wheel speed sensor, DTC C1234 will be set. This DTC can also be set by an excessive wheel speed sensor-to-tone ring air gap or a damaged tone ring.

This pinpoint test is intended to diagnose the following:

Wiring, terminals or connectors
Wheel speed sensor ring
Wheel speed sensor
ABS module