Principle Of Operation Of The Magnetoresistive Sensor
The active sensing of the magnetoresistive sensor is particularly suitable for advanced stability control applications in which sensing at zero or near zero speed is required.
A permanent magnet in the sensor produces a magnetic field with the magnetic field stream at a right angle to the sensing element.
The sensor element is a ferromagnetic alloy that changes its resistance based on the influence of magnetic fields.
As the high portion of the pulse wheel approaches the sensing element, a deflection of the magnetic field stream is created. This causes the resistance to change in the thin film ferromagnetic layer of the sensor element.
Identifying Operation Of Sensor. Scheme 1
The sensor element is affected by the direction of the magnetic field, not the field strength. The field strength is not important as long as it is above a certain level. This allows the sensor to tolerate variations in the field strength caused by age, temperature or mechanical tolerances.
The resistance change in the sensor element affects the voltage that is supplied by the evaluation circuit. The small amount of voltage provided to the sensor element is monitored and the voltage changes (1 to 100mV) are converted into current pulses by the evaluation module.
Scheme 2
- Signal High - 14mA
- Signal Low - 7mA (Scheme 2): Identifying Signal (High And Low)
The sensor evaluation circuit is supplied 12V by the MK60 control unit. Output voltage from the sensor is approximately 10V. The control unit counts the high and low current pulses to determine the wheel speed signal.
Front sensors are three wire because they have a separate ground wire.
Rear sensors are two wire and use the sensor case as a ground point.
Different sensors are used on the left and right side front axle of the vehicle. The difference comes in the length of the harness.
The connectors are blue to distinguish them apart from the grey connectors used for sensors on the MK20 EI.
The DSC III MK60 uses the same metal pulse wheels used with the MK20 inductive sensors.
Identifying Front Axle Wheel Speed Sensor E46/Z3. Scheme 3
Identifying Rear Axle Wheel Speed Sensor Z3. Scheme 4
Identifying Rear Axle Wheel Speed Sensor E46, Short. Scheme 5
There are two types of sensors used in the rear axle of the E46
- The short sensor is used on the 325i (any transmission) and 330i automatic.
- The long sensor is used on the 330i manual transmission version. The Z3 uses the same sensors for the rear axle, left or right.
Principle of Operation
The scope of control for the MK60 DSC III is comprised of three systems
- ABS
- ASC+T
- DSC
Based on signals coming from the various sensors, the MK60 DSC III will determine which system is best suited to maintain control of the vehicle.
In addition to the three basic systems, there are several sub-functions which are activated during very specific circumstances. The sub-functions are
