C0221

C0221 or C021

Circuit Description
As the wheel spins, the wheel speed sensor produces an AC signal. The EBCM uses the frequency of the AC signal to calculate the wheel speed.

Conditions for Running the DTC
Ignition switch in the RUN position.

Conditions for Setting the DTC
The corresponding sensor output voltage is detected as being high (above 3.33 volts) for greater than 0.1 seconds, or low (below 0.039 volts) for greater than 0.5 seconds.

Action Taken When the DTC Sets
^ The ABS indicator lamp turns on.
^ The ABS disables for as long as the malfunction is present.

Conditions for Clearing the DTC
^ Repair the conditions responsible for setting the DTC.
^ Use a scan tool in order to clear the DTC.

Diagnostic Aids
Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Inspect for the following:
^ Backed out terminals
^ Improper mating
^ Broken locks
^ Corrosion
^ Improperly formed or damaged terminals
^ Poor terminal-to-wiring connections
^ Physically damaged wiring
^ Wiring broken inside the insulation
If the customer's concern is that the ABS indicator lamp is on only during humid conditions such as rain, snow, or vehicle wash, thoroughly inspect all wheel speed sensor circuits for signs of water intrusion. Use the following procedure to help isolate the problem area:
1. Spray the suspected area with a 5% salt water solution (two 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 Diagnostic Trouble Code (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, replace the wheel speed sensor. Refer to Wheel Speed Sensor Replacement.