Im wondering is the rad fan switch the larger thread sender or the smaller thread sender? My rad fan wont turn on and my coolant gauge seems like its hooked up to a switch because it will swing from all the way cold to all the way hot in 1-2 seconds, but if I change the senders around it still does the same thing (its not overheating its running at 160 degrees Celsius). Im starting to think this may also be a problem with the coolant temp gauge itself.
did you try another gauge or measure yours? I went aftermarket, both gauge, fan and sensor...works much better anyways...
The rad fan switch and relay system is normally closed. meaning the fan should always be on when the switch is not working. it should only close when the switch cuts the relay. the coolant gauge sender is a very small thread on the water neck with the other sensors. the rad fan switch is on the tstat housing.
