C1221

CIRCUIT DESCRIPTION
The speed sensor is a single point magnetic pickup that produces an AC signal. The Electronic Brake Control Module/Electronic Brake Traction Control Module (EBCM/EBTCM) uses the signal frequency in order to calculate the wheel speed.

CONDITIONS FOR SETTING THE DTC
The LF wheel speed equals 0 and the remaining Wheel Speed Sensor (WSS) speeds are greater than 8 km/h (5 mph) for 2.5 seconds

ACTION TAKEN WHEN THE DTC SETS
^ A DTC C1221 is stored
^ The ABS/TCS is disabled
^ The ABS and the TRACTION OFF indicators are turned on

CONDITIONS FOR CLEARING THE DTC
^ The condition for the Diagnostic Trouble Code (DTC) is no longer present and the scan tool Clear DTC function is used
^ 50 ignition cycles have passed with no DTCs detected

DIAGNOSTIC AIDS
^ Thoroughly inspect the wiring and the connectors. Failure to carefully and fully inspect the wiring and the connectors can result in misdiagnosis. Misdiagnosis may cause replacement of parts without repairing the malfunction.
^ The following conditions may cause an intermittent malfunction:
- Poor connections
- Broken insulation
- A broken wire inside the insulation
^ If an intermittent malfunction exists, refer to Troubleshooting Procedures.

TEST DESCRIPTION
The numbers below refer to step numbers on the diagnostic table.
3. Checks the resistance of the WSS.
5. Checks if the WSS CKTs are shorted together.