[Mk2] [Generic] Vehicle speed signal VSS, ,what kind of signal is it?

[Danbob]

Hello, does anybody know what kind of signal the VSS vehicle speed signal into the stock ECU is?

I'm wanting to use it as an input into my aftermarket ECU, I found something that suggested it output 4 pulses per wheel revolution, however using that doesn't give me a sensible result.

Any ideas?

Thanks
Dan