How do wheel speed sensors work? What is the signal?

[Scott]

I've got a couple of warning lights on the dash of my mondeo, ABS & TC. I don't know if it's a coincidence or not but I recently replaced both rear hubs and the rear discs and pads. In saying this, everything was fine for a couple of weeks so it might actually be coincidence.

 

Anyway, I plugged in my code reader and it's came back all clear. I'm guessing that I need a far more sophisticated and dedicated code reader to get to the bottom of it sooooooooo I was wondering if there is a simple check I could do to make sure the sensors themselves are working (before moving onto the wiring).

 

Will I get a frequency from it? Should there be a resistance over the terminals or should it be open circuit?

 

Just looking for something quick and easy to try and rule things out before paying silly money at a Ford dealership.

 

Cheers

[Nodalmighty]

Reluctor sensors so analogue wave form increasing in frequency with speed. Typically 48 teeth on a Toyota. I assume you meant ABS wheel speed sensors?

 

Lyndon.

[stevie_b]

On a supra, I thought the speed signal was a square wave pulse, 4 pulses for every hub revolution. No idea how that would translate to a Ford, or whether the ABS system works in the same way or not.

[Scott]

Can I use a multimeter to read that frequency? I don't need an accurate representation of what the figure means, I just want to know if the sensor is working or not. Ie, if I plug in my multimeter and set to frequency.... will I actually get anything out of it if it's working? Or do I need to get a scope onto it to get anything from it?

 

I'm just looking to assess if the sensor is working or not. I'm hoping that a frequency read from the sensor means it's OK and that no reading means that it's gubbed. I'm generally not that lucky with ease though lol.