Starter Motor Wiring

[Spikehaus]

I had a quick look at the starter motor wiring today whilst supervising 5 guys trying to make a boat cradle, dont ask...!

The diagrams all seem simple in the book with a feed from the battery to the solenoid, with an output bradded cable to feed the motor. It also has a solenoid connector with a spade terminal.

However the loom from my 1986 Sierra XR4x4i has another cable attached with a copper crimp terminal on the end. Does anyone have any idea what this is for??