Originally Posted by Nouveau Redneck
It would help us in helping you if you mentioned what make and model of tractor it is.
How does that matter. I googled the above title and got some images, but no description of that terminal. It’s just a standard indak key for a magneto type B&S. I’ve got a dozen in my spares box, but none with sixth terminal. Alright, it’s from a Walker T-something (only one with 26hp EFI engine). I looked at the parts and operator manual but neither show the wiring circuit, just wire harness connection. It appears to be a ground as it’s daisy-chained to other devices (and it’s not for illumination); which also means the key has two ground terminals. I know (at least on other magneto tractors) the ground is used for safety circuit. If safety goes to ground they won’t run. Most of my tractors are 30-40 years old and don’t have too much safety stuff.