How to Tell Which Wheel Speed Sensor is Bad
When an ABS light is on, it means there is a problem in the anti-lock braking system. Components of the Anti-lock Braking System are Sensors, switch and controller which are connected through wires. Now there are three sensors in the system, one for each wheel that let the vehicle know when one is about to lock up.
Remove the tire and wheel and inspect for signs of moisture or damage to the outer ABS sensor
- If you have a ABS light on your dash and it’s not one of the 2 rear sensors, it is likely one of the front sensors.
- If there are no signs of moisture or damage replace the outer sensor, if there are signs of damage replace both inner and outer sensors.
- If you have a ABS light on your dash and it’s not one of the 2 rear sensors, it is likely one of the front sensors.
- Remove the tire and wheel and inspect for signs of moisture or damage to the inner ABS sensor. If there are no signs of moisture or damage replace the inner sensor, if there are signs of damage replace both inner and outer sensors
With the sensor removed, inspect for damage to the wires, connectors or wire harness
The wheel speed sensor is a critical part of your vehicle’s electronic control system. It provides information to the computer about how fast each wheel is turning, allowing it to calculate the amount of torque needed for the engine. If you’re experiencing trouble with your vehicle’s acceleration or handling, it might be time to check and replace your faulty wheel speed sensor.
If you’re not sure which part is causing problems, use a voltmeter to measure voltage on each wire between the hub and the sensor. If there is no voltage at one point, then that wire has a short in it which means that either the hub or the sensor are bad. Here’s how:
- Remove any dust caps from the hub and take out all four bolts holding on the caliper bracket (one on each corner). Lift off the caliper and brake rotor together as an assembly, then take off all six lug nuts by hand. Remove all four wheels from the car.
- Locate one of the two wires going from each sensor into its hub . Inspect this wire carefully for damage such as frays in insulation or nicks in copper strands these would indicate that there was
Check for signs of contamination inside the sensor itself that may impede the magnetic field
If there is no contamination, the reason for the failure is likely a problem with the wheel speed sensor itself.
Inspecting the wheel speed sensor for damage, such as cracks or abrasions in its plastic housing. If there is damage to the wheel speed sensor, it should be replaced.
Checking for contamination on or inside of other components in the ABS circuit, such as wiring and connectors. If there is a malfunctioning component besides the wheel speed sensor itself, it should be replaced.
Use an ohmmeter to check the resistance of the sensor
The wheel speed sensor is a magnetic pickup that senses the rotation of the wheel and sends an electronic signal to the ABS control module (or brake controller) to indicate wheel speed. If you find that one or more of your wheel speed sensors is not working properly, it’s important to determine which one is bad.
The following steps will show you how to test your vehicle’s wheel speed sensors:
- Remove the negative battery cable from the battery. This will prevent any voltage spikes from damaging your ohmmeter or other test equipment during testing.
- Using an ohmmeter, measure resistance between each of the various terminals on the ABS control unit (see diagram). The correct resistance readings are as follows:
- Terminal 1: 0-1 ohm (open circuit)
- Terminal 2: 0-100 ohms (open circuit)
- Terminal 3: 0-100 ohms (open circuit)
Perform a voltage drop test on the circuit to check for damaged wiring and poor connections
A wheel speed sensor is a device that is used to detect if the wheels are rotating and at what speed. There are two different types of sensors, one that is used for ABS systems and the second that is used for non-ABS systems. The ABS system utilizes a Hall effect sensor while the non-ABS systems uses magneto resistive sensors.
The wheel speed sensor monitors the rotation of your vehicle’s wheels and tells your vehicle’s computer how fast they are spinning. This information is then used by other onboard computers to apply the brakes when necessary or adjust whether or not you have traction control on.
If your vehicle’s wheel speed sensor fails, you will experience problems with your traction control system as well as your anti-lock brakes. If this happens, it is important to get it fixed as soon as possible so that you can safely drive your vehicle again.
Connect a scan tool and check for active codes in the ABS system as well as systems related to traction control
You can use a scan tool to see if the wheel speed sensor is bad. The scan tool will also show you what code has been set. If there are no faults in the ABS system and no codes related to traction control, then it is likely that a wheel speed sensor is bad.
If you have one wheel speed sensor that is not working properly and another wheel sensor that is working fine, then it may be possible to test the two sensors with a multimeter connected between each sensor and ground.
Conclusion
Wheel speed sensors have the life safety function of controlling cruise control and ABS features. They are linked to multiple systems, pieces of hardware, and are used for critical functions. That’s why diagnosing a bad wheel speed sensor can be quite tricky; you don’t want to be guessing incorrectly on which wheel speed sensor is broken, or having one that’s not working when you don’t know it.
