MagnetoResistive Active Wheel Speed Sensor

BiKenG
Posts: 53
Joined: Tue Feb 10, 2015 12:08 pm
Location: Surrey, UK

MagnetoResistive Active Wheel Speed Sensor

Postby BiKenG » Thu May 28, 2015 8:20 am

I am fitting the Dash 2 Pro to a motorcycle from which the ABS has been removed. Mechanically this is not a problem, but the front and rear WSS were each connected to the ABS ECU which then passed a speed signal for each to the main ECU to use the data for the Traction Control function. I don't particularly need TC, but if the main ECU doesn't see the right signals, it will likely run with engine power permanently cut.

Each WSS is a 2 wire active sensor with 12V supply (from ABS ECU) and the signal is read from the negative return. But this would only be less than 2V and undoubtedly be amplified to about 5V (relative to vehicle ground) before being passed on to the main ECU.

Whether or not the D2P could somehow read this low level WSS output, I need to create a suitable interface to amplify the signals in order to pass to the main ECU (and the D2P will be able to read that).

The circuitry for such an amplification device would I believe be quite simple, but could anyone provide any help with the design? I'm sure it's been done before. Any resources I could study? Or could anyone help with the actual design, from scratch?

Hopefully someone can help somehow.
You can't have too many bikes

Turby
Posts: 296
Joined: Thu Nov 17, 2005 2:28 pm

Postby Turby » Thu May 28, 2015 12:20 pm

This is what Motec have to say on this type of sensor, you may some of info helpful in your quest

http://www.motec.com/filedownload.php/C ... docid=3634

BiKenG
Posts: 53
Joined: Tue Feb 10, 2015 12:08 pm
Location: Surrey, UK

Postby BiKenG » Thu May 28, 2015 4:52 pm

Turby wrote:This is what Motec have to say on this type of sensor, you may some of info helpful in your quest

http://www.motec.com/filedownload.php/C ... docid=3634

Thanks, yes I had seen that, but ultimately didn't think it helped me with circuit design for a suitable amplifier. Rather it was explaining how to allow the Motec Dash to directly read the WSS signal output. I need to 'extract it' and convert to something that can be sent to the main ECU which I think expects a 5V square wave, but the WSS only outputs an approx. 1.6V peak and that's on the negative connection to the WSS rather than a dedicated signal line such as a Hall Effect sensor would provide as that has 3 wires.

I have an idea of what's required, but it's the details I cannot fill in, for which reason I'm hoping for some input from someone with experience of such things.
You can't have too many bikes

BiKenG
Posts: 53
Joined: Tue Feb 10, 2015 12:08 pm
Location: Surrey, UK

Postby BiKenG » Mon Jul 06, 2015 7:01 pm

In the end I dismantled the ABS module so I could remove the hydraulics but still keep the electronic side connected. So the ABS ECU was still able to drive the WSSs and process the output into what the main ECU expected.

I then had to use RT's frequency divider as even the latest D2P is incapable of dealing with a vehicle speed signal at the pulse frequency as used by an ABS system, i.e. with 50-60 pulses per wheel revolution.

But at least it does finally work.
You can't have too many bikes


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