Hi there, A friend just bought his old GTi back off his mate as a non-runner, kept blowing the ECU fuse. After the previous owner spent £250 on an auto electrician spending 4 hours not finding the problem I spent 15 minutes with a light up screwdriver thingy and found the Vehicle Speed Sensor wire had shorted and really killed itself.

Unplugged it, new fuse and drove it away, the seller was a bit pissed but oh well.

I've removed it from the car now and put the Speedo Cable back onto the gearbox.

My question, what does the VSS actually control? will we encounter problems running without it or does it control stupid little things like automatic radio volume or cruise control (which isn't fitted)

 

Well I disassembled it, soldered in a fresh wiring loom to the board, will fit it tomorrow and see if I can burn the thing to the ground :S

 

So not a single person on this site knows what it's actual purpose is?

 

Yes you do need it, on new cars it controls the speedo.

It basically provides the information on the "Vehicle Speed" hence the name to the ECU which then controls idle strategies to reduce emissions when rolling to a standstill.

Martin

 

It is used to detect overrun; - i.e. when the vehicle is moving and you are off the accelerator. When that happens it cuts the fuel for economy reasons.

Without that sensor present the overrun cut off won't work.