ABS - With Traction Control

CIRCUIT DESCRIPTION
As a toothed ring passes by the wheel speed sensor, changes in the electromagnetic field cause the wheel speed sensor to produce a sinusoidal (AC) voltage signal whose frequency is proportional to wheel speed. The magnitude of this signal is directly related to wheel speed and the proximity of the wheel speed sensor to the toothed ring, often referred to as the air gap.

CONDITIONS FOR SETTING THE DTC
DTC C1222 can be set when the vehicle is not in an ABS stop. If the right front wheel speed sensor input signal = 0 and the vehicle's reference speed is greater than 8 km/h (5 mph), a malfunction exists.

ACTION TAKEN WHEN THE DTC SETS
A malfunction DTC is stored, ABS/ETS is disabled, and the amber ABS warning indicator is turned on.

CONDITIONS FOR CLEARING DTC
Condition for DTC is no longer present and the scan tool (CLEAR DTCs) function is used, or 100 drive cycles have passed with no DTC(s) detected.

DIAGNOSTIC AIDS
An intermittent malfunction may be caused by a poor connection, rubbed-through wire insulation, or a wire that is broken inside the insulation. The frequency of the malfunction can be checked by using the enhanced diagnostic function of the Scan Tool. If the customer's comments reflect that the amber ABS warning indicator is on only during moist environmental changes (rain, snow, vehicle wash), all wheel speed sensor circuitry should be thoroughly inspected for signs of water intrusion. If DTC is not current, clear DTCs and simulate the effects of water intrusion. Use the following procedure. Spray the suspected area with a 5 percent salt water solution (two teaspoons of salt to 355 ml [12 ounces] of water). Test drive vehicle over various road surfaces (bumps, turns, etc.) above 24 km/h (15 mph) for at least 30 seconds. If DTC returns, replace suspected harness. Any circuitry that is suspected of 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. Resistance of the wheel speed sensor will increase with an increase in sensor temperature. When replacing a wheel speed sensor, inspect the sensor terminals and harness connector for corrosion and/or water intrusion. If evidence of corrosion or water intrusion exists, replace wheel speed sensor jumper harness. Likewise, if replacing a wheel speed sensor jumper harness, inspect sensor terminals. If evidence of corrosion or water intrusion exists, replace wheel speed sensor.

NOTE: J 39200 test leads must be zeroed prior to making any resistance measurements.





FRONT WHEEL SPEED SENSOR RESISTANCE
This table contains resistance values for the front wheel speed sensors at varying temperatures for use in diagnosis. The values are approximate and should be used as a guideline for diagnosis.

NOTE: Wheel speed sensor intermittent malfunctions may be difficult to locate. Care should be taken not to disturb any electrical connections prior to an indicated step of the diagnosis table. This will ensure that an intermittent condition will not be corrected before the source of the malfunction is found.