1.8T VSS Wiring / Permanent Lives

Afternoon,

I'm guessing a lot of people here have got this sussed, so hopefully I've come to the right place, but I have a couple of questions about the wiring in my 1.8T converted Mk1.

First of all I have not connected the blue and white vehicle speed wire from the ECU. I believe this may be responsible for some hesitation I am experiencing?

Further to this, I am also suffering a moderate sized battery drain. As far as I can work out, the only things which have a constant live are a small red and green wire from the ECU and a red and white from the diagnostic port. Does this sound correct or should either or both of these be ignition lives or wired to certain specific things or similar?

It'd be great to have some help with these little problems and thank you in advance 

There is a good video to diagnose a parasitic drain
How To Perform a Parasitic Draw Test - EricTheCarGuy - YouTube

It will get you to the fuse that is causing the drain, and from there with the Bentley or Haynes you can narrow down the circuit that is giving you fits.

I can't help you with the blue/white wire as I don't do swaps, and stay strictly OEM.  But the speed sensors on the back of the speedo are know to get flaky connections on the cluster and that you may need to plump up your connections by inserting one piece of electrical tape on the pad side of the plastic tongue of the speedo housing.  It makes the pins of the connection tighter.

Remove the shroud off the connector.


Carefully lift the mylar off the tongue.
then place one strip of electrical tape on the tongue and replace the mylar and shroud.

Greatly appreciate the tip regarding the connector at the cluster, and thanks for your time in posting photos to accompany it, I'll get to it

My current thinking on the VSS wire is I could just hook it up to the relevant wire going to the clocks there or maybe even the tacho wire as although that'd be incorrect it would give it a pulsing live so it'd think something was going on and maybe that'd be enough to keep it happy? Who knows!

Thank you again for you assistance

with the VSS first you need GTI MFA type clocks, or certain non-GTI clocks have the connector on the blue foil to allow you to fit one. Then you need to source a spare cluster pin from a donor loom, and pop this to pin 6 of the 6 pin plug on the back of your clocks, feed that to your 20v wiring loom. Jobs a goodun

That is perfect, thank you so much for your help, it makes a great deal more sense now, I just thought I was missing a wire!

Do you recall what the score is with the permanent lives? I have a friend who I believe asked you similar questions to these on Club GTI though I cannot find the thread, his had a battery drain so I'd like to avoid that if at all possible!

Thanks again.

the 2 wires you mention are correct for the 20v loom, assuming the wire colours are as per factory

top suspects for battery drain is if stereo has no switched live and boot light sticking on. old alarm/immobiliser can cause this also.  a bad alternator can also cause a drain.

try the parasitic drain test as above to narrow down which circuit is causing the drain then work from there.  

Also worth noting you may not actually have a drain and your battery is just knackered!