190d block temp sensor
 

My 1985 190d has two single pole sensors to the block. Only one of them is currently wired to anything--I suspect it is the temp gauge. What is the other one for? I also have two cut wires on an adjacent harness with a red wire dangling bareass-- Might this energize the aux fan from that sensor? My aux fan is a replacement, with harness cut (and dead besides) so none of the wires match anything under the hood. Thanks in advance...my cooling system is in general a shambles--the electromagnetic fan is hardbolted so its always engaged and the engine runs fairly hot. Of course, right now (-25f) I could go down the road without coolant if I ran fast enough--but summer is coming...