Golf mk1 Intake Manifold Preheater

 My cars got the old "hedgehog" intake manifold preheater in my engine bay. It's only got a single red wire running from it - this is too short to connect to one of the thermoswitches the engine bay, and instead runs to a matching red wire in the engine bay.


I've no idea what goes on the fourth terminal of the second thermal switch, but I guess it relates to the carb intake manifold preheater? Anyone know?  picture of how it looks off the car:

The white terminal is a live feed and splits to the idle cut off valve and the second thermo switch (the red terminal) , supplying live power to them.

the second red terminal is for the auto choke.

No idea what goes opposite the white connector on the thermoswitch.





Image of the wires in the engine bay:

Thick red one at the back is the intake manifold preheater - goes to a live feed in the dash.

Green on the left is the chokes idle cut off.

Black wire from the autochoke heater goes straight to the coil currently, so it's always on!

Mystery one is the brown wire that looks like an earth, so not sure how that'd help the thermoswitches?