Coolant temperature gauge in cluster/dash.

[RedArrow]

I know, first I should check wiring (8pin connector) and also look at wiring diagrams etc...

The repair:

The corroded and stuck fan at the very front has been disconnected then removed. New fan is not yet bought/found.

The problem:
Coolant temperature gauge in the dash doesn't seem to work now.

The fan has been thrown out, I cant reinstall to re-check the gauge now. Ideas?
Thank you.