C1236

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(Part 2 Of 2):

Sensor Schematic:

CIRCUIT DESCRIPTION
When each wheel turns, the wheel speed sensor creates a small AC voltage with a frequency proportional to wheel speed. This magnetically induced voltage is caused by a toothed sensor ring passing the wheel speed sensor's stationary pickup coil. The toothed ring sensor is mounted on the drive axle in the front, and in the hub/bearing assembly in the rear.

The Electronic Brake/Traction Control Module (EBCM/EBTCM) uses the wheel speed sensor signal to calculate vehicle reference speeds, and individual wheel speed, acceleration and slip values. These values are used to determine when antilock control is required. Vehicles equipped with traction control also use front wheel speed sensor signals to determine when traction control is required.

CONDITIONS FOR SETTING THE DTC
DTC C1236 sets when the EBCM/EBTCM detects electromagnetic interference (noise) in a wheel speed sensor signal. Possible interference sources include accessory motors, wiper motors, ignition circuits and add-on or after market equipment.

DTC C1236 also sets when the EBCM/EBTCM determines a wheel speed signal is erratic. A wheel speed signal indicating that a wheel is accelerating or decelerating faster than physically possible is an example of an erratic signal. An intermittent open or short to ground in a wheel speed sensor could also cause the EBCM/EBTCM to set a DTC.

ACTION TAKEN WHEN THE DTC SETS
A malfunction DTC is stored, ABS is disabled and the ANTILOCK indicator lamp is turned ON.

CONDITIONS FOR CLEARING THE DTC
Conditions for the malfunction are no longer present and scan tool clear DTCs function is used. 100 ignition switch key cycles have passed with no malfunctions detected.

DIAGNOSTIC AIDS
An intermittent malfunction is most likely caused by a poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation. Any circuitry that is suspected as causing the intermittent complaint should be thoroughly checked for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wiring connections or physical damage to the wiring harness.

TEST DESCRIPTION
The numbers below refer to step numbers on the diagnostic table.

4. Ensures that the sensor is capable of putting out the necessary voltage to the EBCM/EBTCM.