VR6 Conversion Alternator Wiring / Battery Light issue

Hi all,

I'm hoping someone on here can help with the issue I'm having. I have a 1990 Mk1 Golf GTI Cabriolet and I've recently completed a VR6 engine swap on. I had a custom loom made which was spliced into the existing Mk1 Loom. Car starts and drives fine but the battery isn't charging, Well, it is but at around 12-12.2volts. I have checked all earth points and even ran a separate new earth from the engine to the battery to see if this would increase the voltage and resolve the issue but it didn't. I've also checked the voltage with the car running at the battery and straight off the alternator and I'm getting the same voltage. Looking at the loom I then found a black single spade plug which runs to the alternator plug. Checked continuity on this cable and all is well but there's nothing on the rest of the loom for this to plug into.

When I put the ignition on, I don't get a battery light at all. so I'm guessing this black cable from the alternator plug needs to get to the original wiring loom for the alternator/ battery light. I'm hoping this all makes some sort of sense. Please see below the photo of the plug if it helps.

Can anyone advised of which cable this may need to attach to on the original mk1 loom / into the fusebox?

I've uploaded a photo to this post so hopefully this will show as I haven't used forums much before.
Thank you in advance, Matt

so after some further searching on here I have found the below:

On the rear of the fuseboard:

Blue multiplug ( 28 pin one) On pin 16 ( Blue Cable) this is for Dash plug T7a/5 alternator warning light.

AND

Yellow multiplug ( 22 pin one) On pin 2 ( blue cable) this is for Alternator Pin D+.

They seem to be the only two wires or pins I can find with anything to do with the standard Alternator/ Clocks warning light.

Does anyone Know If I could trace either of those wires and connect it to the black single spade plug that comes off the VR6 alternator loom and it will then allow me to get a battery light and charge at the correct voltage?

Thank you

the plug you have is for the alternator charge trigger/battery light. this needs to be connected to the blue wire spade near your battery