A wheel speed sensor is a type of tachometer. The wheel speed sensor is a sender device used for reading the speed of a vehicle's wheel rotation. It usually consists of a toothed ring and pickup. Wheel speed sensors are used in anti-lock braking systems in conjunction with the Electronic Stability Control system for increased vehicle control. The ABS or anti-lock brake system uses sensors to transmit data to the ABS module. The ABS systems are activated when a wheel lock is determined. These wheel speed sensors are installed at the wheel and made up of two different components. A reluctor wheel or tone ring seated on the axle which will spin the wheel, and either a magnetic or Hall effect wheel speed sensor which works together to send data to the ABS control module. Over time, the reluctor wheel may become dirty or damaged to the point where it can no longer provide a consistent reading, or the wheel speed sensor may fail. When either of these components fails, the ABS system will not function properly and will require service.
Different cars will have different ABS sensor configurations. Older vehicles may have only one or two sensors on the entire vehicle, while most new ones have one sensor at each wheel. Individual sensors at each wheel allow for more precise readings and improved vehicle performance.
1. The ABS Light is on.
The most visible sign of a problem with the ABS is that the ABS Light will come on. The ABS Light is the equivalent of the Check Engine Light, for the ABS system. When the ABS light illuminates, this is usually the first sign that will be displayed indicating that there may be a problem with the ABS, and perhaps an issue with one of the system’s sensors.
2. Brakes take longer to stop your vehicle.
During heavy braking conditions, the ABS should automatically activate to aid in slowing down the vehicle, and traction loss and skidding should be minimal. While we should try to practice regular driving habits that avoid heavy braking situations, if you do notice that the vehicle is taking longer to stop under heavy braking conditions, or is experiencing traction loss and skidding, then that may be an indicator of there being a problem with the system. The Anti-Lock Brake system is typically made with two components, the ABS module, and the ABS Wheel Speed Sensors. Something wrong with the ABS operation is usually the module or the sensors.
3. Less stability under icy or wet driving conditions
Over time, most drivers will become familiar with how their vehicle handles under certain circumstances, including slippery conditions, such as driving on wet or icy roads. A properly functioning ABS will minimize any traction loss, especially under wet and slippery conditions. If you are driving on wet or icy roads you may experience tire slipping or loss of traction for more than a brief moment when stopping or taking off; then your vehicle's ABS system may not be functioning correctly. Anti-Lock Braking System issues are typically due to either a problem with the module or the sensors.
If your Anti-Lock Brake System or ABS Light comes on, or your vehicle is not slowing down like it used to you may be having a problem with one or more of the ABS sensors, have the vehicle inspected by a professional technician, to determine the exact nature of the problem, and what will correct this issue. These are OEM replacement sensors which will help restore the complete functionality of your ABS system.