Component Location
General Description
The wheel speed sensor is the essential component to the ABS ECU calculating vehicle speed and determining whether wheel lock occurs. For example, rear wheel speed signal is used as a referecnce value of vehicle speed, for front wheel drive vehicles, and if difference between front and rear wheel speed occurs, then ABS control is performed. The wheel speed sensor generates sinewave signals, based on magnetic field made by a permanent magnet in the speed sensor, when the tone wheel rotates. The frequency and AC voltage changes in proportion to the wheel speed, and the HECU determines the speed by calculating the frequeny of the signal.
DTC Description
The ABS ECU monitors the wheel speed sensor signal continuously. This code is set if the ABS control cycle is continued abnormally. Warning lamp is turned OFF unless fault is detected any more when the IG KEY is turned ON again, and wheel speed is more than 12 Km/h.
DTC Detecting Condition
Item | Detecting Condition | Possible cause |
Case1 | DTC Strategy | ? ABS continuous control monitoring | ? Improper installation of wheel speed sensor ? Abnormal Rotor and wheel bearing |
Monitoring Period | ? Continuous |
Enable conditions | ? Continuous ABS and EBD control for a time period >= 60s at one or more wheels |
Fail Safe | ? ABS is switched off immediately. ? The ABS and the EBD warning lamps are activated. ? Continuous ABS and EBD control of the appropriate wheel(s). The wheel may not have sufficient braking capacity. |
Case2 | DTC Strategy | ? Static Wheel Slip monitoring |
Monitoring Period | ? Continuous |
Enable conditions | ? Vehicle > 100Km/h 1. deviation of two wheel speeds at either side of the vehicle > (6% * vehicle speed) or at the front axle > (4Km/h + 6% * vehicle speed) ? Detection filter time The detection time is dependent on the amount of the deviation as shown below. 1. 20s - if fault threshold is exceeded by > 0Km/h (%) 2. 13s - if fault threshold is exceeded by > 3Km/h (%) 3. 10s - if fault threshold is exceeded by > 6Km/h (%) ? Mini spare wheel detection If only one single wheel is within the allowed mini spare band, wheel slip monitoring is temporarily disabled. ? Spinning wheel, decelerating wheel 1. If any wheel is doing a shows strong deceleration (e.g. caused by hand brake) the fault detection filter time is set to 20s. 2. If any spinning wheel is detected the fault detection filter time is set to 80s. |
Fail Safe | ? If the location can not be determined, a general tone wheel fault is stored. (At the time of detection no wheel speed is at Vmin.) In this case: ABS and EBD is shut off immediately. ? ABS and EBD control of a faulty wheel is not longer possible. ? The ABS and the EBD warning lamps are activated. |
Schematic Diagram
Full Circuit