Hello everybody,
this is my first post, so be gentle with me, hehehe.

I have recently had the head rebuilt on my ST170, the problem is, for love nor money can I find where this plug goes???

I don't know how to attach a pic so I will describe it.

It's a very short thin 2 wire grey plug in the same loom as the temperature sender in the top of the thermostat housing.
Infact it looks similar to the thermostat housing temp sender.
The big label stickered to the loom reads

2M5V-9H589
AD

Any ideas would be greatly appreciated,
thankyou