What Does A Bad Speed Sensor Cause A Vehicle To Do?


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Charlie Proofer Profile
Charlie Proofer answered
A wheel speed sensor or vehicle speed sensor (VSS) is a type of tachometer. It is a sender device used for reading the speed of a vehicle's wheel rotation. It usually consists of a toothed ring and pickup.

Defective vehicle speed sensors can cause many problems in the computer output control systems. Speed is used by the control module as an input for many systems. If the input is bad then the output will not be good either. Defective vehicle speed sensors may cause improper torque converter clutch lockup as well as cruise control malfunctions. A bad VSS can also cause inaccurate speedometer operation. It is really helpful to have the vehicle hoisted up on a lift so that the drive wheels can spin freely when you attempt to diagnose vehicle speed sensor problems.

When it is not possible to have a safe way to spin the wheels without moving the vehicle, it may be necessary to take the vehicle in to a professional for proper diagnosis. There are a few checks that can be made to vehicle speed sensor without spinning the wheels. One test would be to connect an automotive electrical volt ohm meter and get an accurate resistance reading on the sensor.

The internal resistance of the sensors measured across the sensors terminals should typically range around 1000 ohms. But a good sensor can be lower or higher depending on the application as it seems about 800 to 1400 ohms of resistance would be a passing grade. Wheel speed sensors and vehicle speed sensors are both permanent magnet voltage producing sensors and the procedures for testing both of these automotive electrical components are very similar. Factory service manuals include diagnostic routines and tree charts that can help technicians quickly diagnose VSS problems. Once they have diagnosed the problem, then they will be able to advise you on the most appropriate course of action.
Anonymous Profile
Anonymous answered
My 4X4 2004 Explorer has a bad speed sensor and my vehicle jumps in and out of 4 high and 4 lo. The ABS light is also on because the sensor is getting incorrect information. It is a fix of about 400.00 or so because you have to get a new hub that has the sensor attached. You need to have your vehicle put on a code reader to see what about the sensor is bad. It might just need cleaning or only one part of the sensor repaired. There are rings on each wheel that send info to the sensor so it can do its job. Possibly only a ring is bad. Hope this helps. Diane R.
Anonymous Profile
Anonymous answered
We have just been told that we need a new sensor on my husbands 2008 Ford Explorer with only 18,000 miles. The car would all of a sudden start jerking and steering became very difficult. We would also hear a strange noise coming from what seemed like the wheels. Could never really pinpoint the noise. I hope they are on the right track.
Jon Profile
Jon answered
Funny thing, actually. It gives it magnetic traits. It tends to draw blue and red flashing lights to it  (in other words, if you don't know how fast you are going, how can you know that you aren't going too fast?).

Aside from getting tickets, a bad speed sensor shouldn't have any adverse affects.

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