Speed sensor problem

rocar · Post by **rocar** » Thu Feb 12, 2015 11:58 pm

I fitted a speed sensor on S60 and Xdash and with engine off it work perfect by turning undriven wheel but as soon engine start speed goes crazy and goes from 300 to 600 kph without turning wheel
http://www.race-technology.com/wheel_speed_2_61.html
http://www.race-technology.com/wiki/ind ... WheelSpeed
I tried another one but the same
I used to use the old type on other cars with no issues, I tried an old type sensor from another car and worked fine so it seems something wrong with the new type sensors
As I not an electronic genius is the anything to do to use these sensors

Emailed to Allan and he said it is probably an electrical noise issue.

Is there a solution?

katana · Post by **katana** » Fri Feb 13, 2015 12:52 pm

Screened, twisted pair cable with all screens tied to common ground point should cure that.

stevieturbo · Post by **stevieturbo** » Fri Feb 13, 2015 3:24 pm

Are there any HT leads near the wiring of the sensor ?

Maybe try pulling the sensor out of the way entirely with the engine running and see if it's still the same ?

rocar · Post by **rocar** » Tue Feb 17, 2015 3:25 am

No HT and took out sensor away from car but the same, tried screened wire, a bit better but it did not cure problem.

stevieturbo · Post by **stevieturbo** » Tue Feb 17, 2015 3:45 am

I wonder would adding a small resistor either inline or parallel to the sensor dampen any interference spikes ?

I've only ever used the GT101 with mine for wheel speed

I did try a threaded hall sensor briefly for the cam sensor, it wasnt that reliable though but never investigated why as I changed ecu just after it.

rocar · Post by **rocar** » Tue Feb 17, 2015 4:30 am

Hi Stevie,
Sorry I do not understand inline or parallel?

stevieturbo · Post by **stevieturbo** » Tue Feb 17, 2015 10:40 am

Again, electrically a resistor may not be the correct thing to use to help quieten or smooth interference. Some of the more electronically smart guys could advise.

As to placement of any resistor and value, again not sure.

But series and parallel explained ( just like batteries are connected to either increase ampage, or voltage )

stevieturbo · Post by **stevieturbo** » Tue Feb 17, 2015 10:49 am

http://www.kerrywong.com/2012/01/26/a-s ... reduction/

The above mentions a low pass filter, which seems to be a small resistor and capacitor

http://en.wikipedia.org/wiki/Low-pass_filter

You also see a lot of gear sold with a ferrite core on the power lead which is used to filter noise

http://www.ebay.co.uk/bhp/ferrite-core

Not sure if you'd only use this for the signal wire, or all cores

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