C0221

Circuit Description
The wheel speed sensor coil emits an electromagnetic field. A toothed ring on the wheel passes by the wheel speed sensor and disrupts this electromagnetic field. The disruption in the field causes the wheel speed sensor to produce a sinusoidal (AC) voltage signal. The frequency and amplitude of the sinusoidal (AC) voltage signal are proportional to the speed of the wheel. The amplitude of the wheel speed signal is also directly related to the distance between the wheel speed sensor coil and the tone wheel. This distance is referred to as the air gap.

Conditions for Running the DTC
^ The ignition switch is in the RUN position.
^ The vehicle speed is greater than 13 km/h (8 mph).

Conditions for Setting the DTC
^ No output signal from the right front wheel speed sensor for 1.0 second
^ Excessive right front wheel speed sensor resistance for 1.0 second

Action Taken When the DTC Sets
^ The ABS indicator lamp turns on.
^ The ABS disables.
DTC C0221 is a Condition Latched DTC, which indicates that the above actions remain true only as long as the condition persists.
DTC C0221 is a DRP non-critical malfunction. If any other DTC sets before this DTC is investigated and cleared, this will become a DRP critical malfunction and the BRAKE indicator lamp will also turn on.

Conditions for Clearing the DTC
^ Repair the conditions responsible for setting the DTC.
^ Use the Scan Tool Clear DTCs function.
^ A Condition Latched DTC may exist momentarily or constantly. In either case, the DTC will be stored in the EBCM memory until the DTC is repaired and/or cleared. After the DTC is repaired and/or cleared and the ignition switch is turned to the ON position, the ABS lamp will remain lit until the EBCM completes the power-up self test. This test concludes when the vehicle has reached a speed of greater than 13 km/h (8 mph) and the wheel speed inputs have been checked by the EBCM.

Diagnostic Aids
Any of the following conditions may cause an intermittent malfunction:
^ A poor connection
^ Wire insulation that is rubbed through
^ A broken wire inside the insulation
Thoroughly check any circuitry suspected of causing the intermittent complaint for the following conditions:
^ Backed out terminals
^ Improper mating Broken locks
^ Improperly formed or damaged terminals
^ Poor terminal to wiring connections
^ Physical damage to the wiring harness
If the customer says that the ABS indicator lamp is on only during humid conditions such as rain, snow, or vehicle wash, then thoroughly inspect all wheel speed sensor circuits for signs of water intrusion. Use the following procedure:
1. Spray the suspected area with a 5 percent salt water solution (2 teaspoons of salt to 12 oz of water).
2. Drive the vehicle above 24 km/h (15 mph) for at least 30 seconds.
If the DTC returns, replace the suspected harness.
When inspecting a wheel speed sensor, inspect the sensor terminals and the harness connector for corrosion. If evidence of corrosion exists, then replace the wheel speed sensor. Refer to Wheel Speed Sensor Replacement.
Resistance of the wheel speed sensor will increase with an increase in sensor temperature. Refer to ABS Diagnostic Specifications for WSS temperature/resistance values.

Test Description
The numbers below refer to the steps in the diagnostic table:
4. This step tests the wheel speed sensor for the proper resistance value.
5. This step ensures that the wheel speed sensor generates the proper voltage.