Andrew Cripps Posted July 17, 2011 Report Share Posted July 17, 2011 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  Andrew Quote Link to comment Share on other sites More sharing options...
Simon Posted July 20, 2011 Report Share Posted July 20, 2011 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. Quote Link to comment Share on other sites More sharing options...
Andrew Cripps Posted July 21, 2011 Author Report Share Posted July 21, 2011 Hi Simon Thanks for that but my speed sensor is the cog driven type, (i think it could be a AC unit????) Â if it is, is the wiring the same as you mentioned? RB25DET nissan speed sensor. Thanks Andrew Quote Link to comment Share on other sites More sharing options...
Simon Posted July 22, 2011 Report Share Posted July 22, 2011 As long as its a two wire sensor then it will still have the same wiring. Quote Link to comment Share on other sites More sharing options...
Reece Bartholomew Posted July 25, 2011 Report Share Posted July 25, 2011 Couldnt you just wire it straight into the factory speedo wire into the ecu for the same effect? Quote Link to comment Share on other sites More sharing options...
benjames Posted March 6, 2016 Report Share Posted March 6, 2016 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! Quote Link to comment Share on other sites More sharing options...
Scott Posted March 7, 2016 Report Share Posted March 7, 2016 Of the two wires, one goes to the digital input channel, and the other goes to one of the ECU's sensor ground pins. Do not use the negative terminal of the battery. benjames 1 Quote Link to comment Share on other sites More sharing options...
benjames Posted March 12, 2016 Report Share Posted March 12, 2016 Awesome, thank you Scott Quote Link to comment Share on other sites More sharing options...
benjames Posted April 30, 2016 Report Share Posted April 30, 2016 (edited) 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! Cheers! Edited April 30, 2016 by benjames Quote Link to comment Share on other sites More sharing options...
Scott Posted May 2, 2016 Report Share Posted May 2, 2016 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. Quote Link to comment Share on other sites More sharing options...
benjames Posted May 2, 2016 Report Share Posted May 2, 2016 Right, so to clarify, I don't need to determine which pin out of the sensor is which, I can just allocate the DI and earth randomly?Thanks Quote Link to comment Share on other sites More sharing options...
Scott Posted May 2, 2016 Report Share Posted May 2, 2016 It will work either way round, you may have to try both falling and rising edge settings. Quote Link to comment Share on other sites More sharing options...
benjames Posted May 2, 2016 Report Share Posted May 2, 2016 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. Quote Link to comment Share on other sites More sharing options...
Scott Posted May 2, 2016 Report Share Posted May 2, 2016 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. Quote Link to comment Share on other sites More sharing options...
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