MR Wheel speed input config ?

Discussion and Support for MoTeC's M1 series ECUs

MR Wheel speed input config ?

Postby oversteer on Wed Apr 23, 2025 9:08 pm

Hello

I have MR wheel speed sensors from a BA-FG Falcon that I want to get a signal from with an M150, there is no abs in play, rear ford irs cradle is in a HK holden.

I have sensor + to 12v and - to UDIG with a 270ohm pulldown to sensor ground, I do get a signal from this with voltage range of ~ 2-3.8v, the issue is that the signal seems to fall off as speed increases or rather speed doesn't increase at expected rate !

I have threshhold set to 3v with 0.2v hysteresis and 5us debounce, that seems to work best so far, tone rings on CV's have 50 teeth

Looking at sensor voltages in log I can see it starts to flatten or get clipped.

Should this voltage range work fed into a M150 UDIG ? or do I need a different wiring arrangement for a better
signal ?

Log file https://drive.google.com/file/d/1P7U2to ... sp=sharing
Package https://drive.google.com/file/d/1qqAla0 ... sp=sharing

Thanks
oversteer
 
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Re: MR Wheel speed input config ?

Postby NathanB on Thu Apr 24, 2025 10:29 am

With no other point of reference, there is no way to validate you feeling on how the speed should be reporting.

Wheel speed.png
Wheel speed.png (448.73 KiB) Viewed 36 times


All the data points seem to indicate everything is fine and we don't see a change in the reported min/max.

If you had a concern with the wheel speed signal at speed, I would suggest an input capture completed on udig 1-4 at once it is run up through the gears (I'm guessing the car is on stands) and check the signal at speed.

That is the only way to tell what is happening with signal voltage, as the capture will likely be at around 100,000hz instead of 50.
NathanB
MoTeC
 
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