1G Is it possible to custom make ABS wheel speed sensors?

[XC92]

Several years ago I completely rebuilt my '92 AWD Talon's rear end, taking everything apart to clean it up, remove all the rust, treat and paint all the parts and replace some bushings and other parts before putting it all back together again.

In the process, though, I destroyed both ABS wheel speed sensors when trying to remove them, a common occurrence with these cars given their age (oddly the front sensors came out fine). I should have instead just disconnected their connectors. But I didn't and nothing I can do about that now. The old sensors are toast.

Assuming that they're even in stock, new ones are pricey at several hundred $$ each. I could try junk yards but these cars and parts are getting pretty hard to find, and given how common it is that they're destroyed when removed I doubt I'd have much luck there.

So what I was thinking of doing is essentially making my own sensors. I assume that they're Hall Effect, so I'd have to find ones as close to the stock ones as I can, and find a way to safely and reliably install them back in the trailing arm so that they don't come out, fall in, and get good readings. If necessary, I'd have to add some basic circuitry to get the voltages per spec, then just patch them to the stock cables.

Is this feasible and has anyone tried this? Yes, I know, real DSM owners delete or don't use or need ABS, and honestly I've rarely needed them. But the car has ABS capability which I'm not going to delete, so I might as well get its functionality back and have that annoying ABS light go off w/o having to pull the fuse.

Btw, is there any way that this could actually be dangerous, by sending the ABS computer bad signals and trigger an ABS activation at the absolutely wrong time?

 

[danl]

Can you post a picture of the sensors. They might be common on other models. In general if a new sensor works, you are good. It is simply a magnetic tone ring inducing a current in the sensors coil which is them picked up by the abs computer. The output will be a pulse with a certian peak voltage. If you are concerned with getting the right signal to the abs computer you will need to get an oscilloscope on the sensor with the wheel moving. You only need a $60 oscilloscope. The FSM may state the proper voltage output. Otherwise take the signal from a working front wheel.

The main risk of making your own is the sensor voltage being on the edge of what the abs computer registers as a good signal. If it senses loss of signal and interprets that as a locked up wheel, the abs will activate. On some cars like chevys this can make it very difficult to get stopped.

 

[XC92]

Can you post a picture of the sensors. They might be common on other models. In general if a new sensor works, you are good. It is simply a magnetic tone ring inducing a current in the sensors coil which is them picked up by the abs computer. The output will be a pulse with a certian peak voltage. If you are concerned with getting the right signal to the abs computer you will need to get an oscilloscope on the sensor with the wheel moving. You only need a $60 oscilloscope. The FSM may state the proper voltage output. Otherwise take the signal from a working front wheel.

The main risk is the sensor voltage being on the edge of what the abs computer registers as a good signal. If it senses loss of signal and interprets that as a locked up wheel, the abs will activate. On some cars like chevys this can make it very difficult to get stopped.

I don't think that a photo would help and I might be able to reuse the bracket part, but I stored it somewhere and would need to dig it up. I likely wouldn't tackle it till the spring as it's not a critical fix right now. And given that this is an AWD I'd have to detach either the prop shaft or CV axle to turn the wheel fast enough to test the output of any jerry-rigged sensor I put in there.

Btw is it indeed hall effect, or just magnetic? I still have the actual sensor "prongs" that interact with the tone ring, so perhaps it would be possible to strip away the packing material and rewire it, and put some bushing-grade rubber or poly around it to hold it tight when reinstalled. I don't have a scope but I could probably rig something good enough for this one project, with an Arduino or such. And there are probably inexpensive phone app-based ones out there.

 

[curt-s]

Just dont get the 2C23T oscilloscope.
It was such a POS it went back in less than a day.