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Speed sensor wiring

Andrew Cripps

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Hi guys

first off i would like to say how impressed i am with the new g4 link plug in computer i have just brought and had installed. Im also running the display link dash and think its great value for money. i was running the old g1 link gts on a rb30det and this one is much better.

My question is about the speed reading on my dash (that isnt working). i would like to run the gear selection on the dash but looking on the help menu file on the pc link software i need the speed reading. Im running the rb25det big gearbox with the electronic 2 wire speed sensor (green and green). it seams to be all hooked up but the factory wiring loom must have a short in it somewhere. im going to rewire the entire speed signal cct and wire it directly to the link, and not use the factory dash at all.

i have checked in the supplied link paper work and the speed signal on my computer is DI3 which on the computer loom is plug 53. what i would like to know is how to wire the speed signal, obvisualy one side of the speed sensor goes to treminal 53/DI3 but where does the other wire from the speed sensor go to? and what changes will i need to make in the computer software?

Thanks for any help you can give me



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One side of the sensor will be ground. The other will go to the Di.

The polarity will need to be checked.

The easiest way to do this will be to remove the sensor and use a multi meter on volts.

When you bring a metal object up to the sensor you want to see a positive voltage spike.

When you pull the object away it should go negative.

If not swap the leads over.

Wire the positive lead is connect to is the signal the other is the ground.

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  • 4 years later...

Hi, I'm trying to work out my ECU wiring now and stuck on the VSS... (Same R34 2 pin sensor) the wire that produces the + output goes to the DI ECU pin, and the other goes to a 'sensor earth'? or does it need to be earthed separately to the battery?


Thanks! :)

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  • 1 month later...

Hey Scott,

I'm not able to make my VSS generate a positive output from either wire. I'm spinning it up in the drill to simulate speed.

Spinning the sensor both ways and, swapping multimeter pins, still all neg. 

Or does the wiring for this type not need specific wiring, I can simply wire the earth to either of the two wires and the DI to the other wire?

What am I doing wrong! 



Edited by benjames
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Putting it in a drill will not work, as the magnetic field is building positive and then negative, and so when measured on a multimeter is will most likely be cancelling out. If you were looking at the signal on an oscilloscope you would see a sin wave form. On the ECU, connecting one pin to sensor ground, and the other to a digital input channel will work fine. 

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Okie dokie, thanks again Scott! :)

I figured , and was worried, that if I stuffed up the polarity I'd charge the earth wire and damage the rest of the sensors that share that common sensor earth.

The polarity is more to do with how the signal crosses the 0v line when set to falling. In the following images the polarity is correct in the upper image. The signal falls straight down through 0v, where -as on the 2nd image the line is at zero for quite a while. When it comes to things like crank and cam position sensors this can be really important, but with wheel speed it is not crucial, as what matters is the frequency, rather than the time that 0v is crossed.


Reluctor wave.PNG

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