VSS Wire colours

[alfalfa155]

I am trying to fit what I think is a mk1 Punto vss to my alfa. They are the same except for the wire colours.

I have brown, yellow-black, and light blue. I have combed the web and my wiring diagrams to find a match, but to no avail. Can anyone tell me which is +ve, earth, and pulse return so I can test it??

 

[alfalfa155]

Anyone at all...?

 

[s130]

Pray what is a VSS?

 

[alfalfa155]

Sorry, vehicle speed sensor

 

[s130]

Your wire colours do not match the information I have for a MkI Punto.

I think you are going to have to use a multimeter to sort those wires out.

Shouldn't be difficult.

a) With luck one, the ground wire may be connected to the body.
b) Another pair should pick up a coil impedance
c) The other should be the pulsed output

You need to check for the presence of any diodes or voltage polarity devices. There shouldn't be any but if you do all the permutations and combinations of the three leads with the meter leads in one direction and then repeat with the meter leads swopped over then you can build yourself an impedance/resistance chart.

Also spinning the sender unit will cause a larger impedance/resistance change in one of the measurements. This is almost certainly the pulse output.

If possible use a traditional analogue multi-meter to examine impedance changes as the movement of the needle is far more accurate and continuous than a sampled reading off a digital multi-meter.

 

[alfalfa155]

Thanks, got it figured out. Blue is positive, brown earth and yellow signal. Speedo working!