5 replies to this topic

[kimbo]

Final stages of my build.  Trying to sort out the speedo.   So I have a EA falcon T5 with its VSS (Transducer or Speed Sensor) and 3 wires.  There is a lot of conflicting info on the net and I may have already fried the sender.  Anyhow some say the Black = Grd, White = 12v Power, Blue = Signal.   Others say the white = Signal and Blue = 12v Power.   Some other guy reckons the power feed needs to be 8.2V.   Out of the Speedhut cluster is a Black = Grd and a White = Signal.  I have run a power wire to suit the Ford VSS as is required apparently.

 

Has anybody messed with this setup before and can enlighten me to what is actually correct?

 

Cheers 

[76lxhatch]

3 wire sensor sounds like hall effect so yes it will need an input voltage as you say. I'm not familiar with Ford colours but white is commonly signal wire, I'd probably try that first. Hook it up to a power supply on the bench and test with a multi-meter, you should be able to see the voltage on the signal wire go high and low compared to the ground as you turn it.

 

The Speedhut gauge I have says it will accept a signal from 1-100V on the white wire, so provided the sensor actually works correctly and outputs a non-zero voltage I doubt it matters exactly. This document indicates that it will work with a hall effect sensor:

https://speedhut.com...nstructions.pdf

You shouldn't need any sort of pull-up or pull-down resistor with the hall effect sensor. The sensor ground from the speedo should be directly connected to the sensor's ground wire. The speedo will have its own power and ground as well.

[kimbo]

3 wire sensor sounds like hall effect so yes it will need an input voltage as you say. I'm not familiar with Ford colours but white is commonly signal wire, I'd probably try that first. Hook it up to a power supply on the bench and test with a multi-meter, you should be able to see the voltage on the signal wire go high and low compared to the ground as you turn it.

The Speedhut gauge I have says it will accept a signal from 1-100V on the white wire, so provided the sensor actually works correctly and outputs a non-zero voltage I doubt it matters exactly. This document indicates that it will work with a hall effect sensor:
https://speedhut.com...nstructions.pdf
You shouldn't need any sort of pull-up or pull-down resistor with the hall effect sensor. The sensor ground from the speedo should be directly connected to the sensor's ground wire. The speedo will have its own power and ground as well.

So what do you reckon? I have a 50% chance of hooking up the 12v to signal wire. These things are hard to find and expensive so not really wanting to fry it. Any opinions here?

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[76lxhatch]

I told you how to test it before hooking it up...

[kimbo]

I told you how to test it before hooking it up...

Yeah in know. I was just thinking 12v on the bench is similar to 12v in the car. Wasn't sure if I wired it wrong on the bench it would fry or be OK. Anyhow took a punt and tested with the white as signal. I get uniform fluctuating voltage pulses on rotation. However voltage seems to be a wave form not a square wave. I think hall effect senders would be 12v on then off correct ? I am getting less than 12v in fact it's either just over or just under 1v. Wondering if these are even compatible with the speedhut gauges. You can buy a Ford style T5 connecter (uses Ford gears etc)but with a GM VSS attached. These are definitely Hall Effect.

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[76lxhatch]

It can't really be anything but hall effect with those connections, and not sure how you'd be able to tell the difference without a scope. If you're only using a digital multimeter you probably won't get an accurate reading of voltage as they have a significant delay.

 

You've proved it works and doesn't do anything untoward, now hook it up to the speedo and see if you get a reading.