I installed a remote start a little while ago, and after checking my notes wonder what year 740 turbo you have. Mine's an '86.

The pink wire should be the starter- that's what mine is.

The Red wires are the constant power source.

The thin Yellow/White is most likely the key reminder wire.

I used the Blue/Red as ignition #1 (according to my notes- double check with voltmeter).

My notes read that Blue/Yellow are the accessory wires.

My notes read that Ignition #2 was a fat and a thin black wire connected to position "X" on the connector.

You should be able to disconnect the wiring harness from the switch by simply disconnecting it from the rear of the switch. I did this by simply removing the instrument cluster. Ignition 1 should be the wire connected to position "15" and Ignition 2 should be connected to position "X".

One way to confirm the wire colors is with a schematic drawing like you would find in the back of a Haynes manual.

The best way to confirm is to skin the wires where you might splice into them, and confirm voltage is present at the appropriate key position.

Good luck-
Dylan