C1221

DTC C1221: LF Wheel Speed Sensor Input Signal = 0:

DTC C1221 Schematic:

CIRCUIT DESCRIPTION
The speed sensor used on this vehicle is a single point magnetic pickup. This sensor produces an AC signal that the Electronic Brake/Traction Control Module (EBTCM) uses the frequency from to calculate the wheel speed.

CONDITION FOR SETTING THE DTC
The Diagnostic Trouble Code (DTC) will set if one wheel speed = 0 and the other WSS are greater than 8 km/h (5 mph) for 2.5 seconds.

ACTION TAKEN WHEN THE DTC SETS
A malfunction DTC is stored, ABS/TCS is disabled and the ABS and TRACTION OFF Indicator lamps are turned ON.

CONDITIONS FOR CLEARING THE DTC
Condition for DTC is no longer present and scan tool clear function is used. Fifty start cycles have passed with no DTCs detected.

DIAGNOSTIC AIDS
It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction. An intermittent malfunction can be caused by poor connections, broken insulation, or a wire that is broken inside the insulation.

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.