dash lights and gauge problem

great stuff

My new problem is this, as I was looking for the wires for the reverse switch in the fuse box, the wires touched the fuse box somewhere and there was a spark, from that point on the oil pressure indicator on the dash does not work, it has not burned out either fuse but not any lamp on the dial.

I'm thinking to avoid messing with the fuse box again I'll run a separate wire from the oil pressure switch straight to the dial. Will it work like this? Is there anything I should watch out for…?

Is this a separate gauge, or the oil light in the cluster?
If the light is in the clocks, then does it light with the key on and the engine not running.

It is not a separate gauge. It's the oil light in the cluster and it's dead. It is not light with the ignition on. The cluster has no problem I checked it. The bulbs in the cluster are new.

if you earth the yellow wire for the low pressure switch, the light should come on. if you disconnect the blue/black for high pressure switch light+buzzer should come on at around 2k rpm (if equipped)

Before messing with the new wire i' ll try to earth the yellow wire (i believe green in my car for some reason…).  My car does not have high pressure switch.

I found what caused the spark in the fuse box. I put 12V on the pin G8 in the fuse box leading to brake light switch witch is connected internally with D18 pin witch is pin 10 on the cluster (oil pressure switch ).

So now i have either a broken my new oil pressure switch (if these things brake) or a fried wire leading to engine or to the cluster…

And I am still having troubles to connect the reverse switch to the fuse box.   

I guess you meant which G/9 is the brake switch terminal, and yeah it would have been earthed if the engine was off. doubt it would have damaged the switch but maybe crisped a wire though if it was only briefly you're probably fine

possibly you damaged the blue foil on the cluster though, if the 12v managed to find a path to ground thru it somewhere

Yes correct it was G9 pin.

The cluster is fine. I have 2 of them and 1 wasn't connected to the car when i fried the wires, and it was working fine.

So that I don't have to look for which wire is melted, Can I pull a new wire from the oil pressure switch to he cluster.

Will it work like this or will I have more problems

you can do this yep, for a quick test with the ignition on simply poke a wire in the back of the cluster pins between the earth and oil pressure switch pins, the light should come on.

most if not all the mk1 cluster pinouts are in my guide:
https://clubgti.com/forums/index.php?threads/fusebox-faq.219775/

if there is a wiring fault in the engine loom but cluster harness is fine, you could run a wire from G/9 straight to the oil switch instead, saves splicing into the dash harness

Ok thanks, I 'll try to find the crispy wire.