Ignition Electrical issue

Hi

20 years ago while driving my mk1 I lost all power to everything,
I got a wire from a permanent live and touched each fuse in turn till power came on, this was on fuse 17 which at the time I presumed was fuel pump.
I rigged up a toggle switch and ran a permanent live and jammed it in the 17 slot with the fuse.
This worked fine for years, still does.
However I'd like to fix it properly

Now I realise fuse 17 is something to do with the ecu.

So I replaced the whole fuse board the other day as my one had signs of corrosion.
Didn't fix anything, but having a spare I can now bell out connections which is helpful as I can't find my haynes manual and never seem to find the correct drawings online.

I think regarding the fuses the power comes in from the bottom of fuse and back in, in the top of the fuse, so with my meter jammed in the bottom of fuse 17 it bell's out to pin 2 on connector plug D (the white one)

Great, now I know what wire to trace…no I have no wire in plug for pin 2 in socket D

So I don't know how fuse 17 ever got power.

What am I missing here,

the car has a 16v conversion done by previous owner in 1998.
Is there another way they would of got power to the ecu?

I just want to know what wire to trace.

Or could it be a faulty immobiliser?

I may remove the immobiliser this weekend to rule that out.

I would love to get to the bottom of this 20 year old problem

It's a 1982/3 mk1 gti tin top

Thanks

Don't think it's immobiliser as when immobiliser is on the car wont crank, touch the fob then the car will crank but have no dash lights until I manually add power to fuse 17

I was a bit hasty in my post, found other pins it bell's out to, there may be hope yet

Turns out it was my immobiliser, it seemed fine as it armed and disarmed fine, but black wire 15, ignition live was going into the immobiliser but not coming back out, how I didn't spot this 20 years ago I'll never know,
Just thought I'd be courteous and put a conclusion to this thread incase anyone else stumbles on it, so many forum threads I read have no conclusion to them, never know if a problem is solved or not