The Rover-Landers of BC

Hey guys.
Need help figuring out what this switch and wire might be for. Truck has been heavily rewired.
Its a simple on off switch on the lower right dash of an s2a. Probably not standard.
It gets power only with key in start position. Has a long wire that can reach the front of engine bay or back to about mid truck.
Truck was running a naturally aspirated diesel engine previously.
Any thoughts on what it might be for?

fuel pump?

But its only live when the key is in the momentary start position not the run position. Not sure if fuel pump would make sense

Also. In addition to the key start position to crank there is a separate crank switch (i assume) in center dash. So maybe someting to do with glow plugs?

Lots of possibilities... heater motor, electric radiator fan, power supply to a relay for auxiliary lights, interior lights, back-up lights (examples of what my series rovers have had)...

Do any of those make sense to be live only on key start (not run start, just start)

Must have sonething to do with the ignition circuit. Wires are on 12ga... Maybe 14...
Might not matter as i have to redo the ignition circuit anyway

Whoops, misread the post regarding the "start" position. :oops:

Now I'm thinking it is a low-tech anti-theft device, power circuit to the starter solenoid to prevent someone from starting it without flicking the right switch?

If it is powered in a position between on and start it is for glow plugs.

I've seen a wire like that for an exciter circuit to a (non standard) alternator. Some after market alternators need a initial exciter voltage to get them kick started. :dontknow:

My first thought was glow plugs but never dealt with diesel before. I think the ignition switch is from a petrol rrc so that might explain the muckery.

Now that i know i can put my mind to rest :)