OK, so I want to add some ideas to this because I've seen some great threads on others sites about the temp sensor set up. I give FULL credit to 99.8% of this to this thread: http://www.nastyz28.com/forum/showthread.php?t=200028
HOWEVER for jeepers we need to have a temp sensor that works.... so here is MY setup;
1 x jeep CJ8 with a 4.0 head and MPFI (not necessary but you gotta have A VEHICLE)
1 x Contour 2 speed, 2 fan - I have elected to use the resistor in the bottom left of the fan so that two fans come on with first trigger, stay on but increase speed for 2nd trigger.
1 BMW 2 temperature sensor - 61311378073 from a BMW 90's, always screwed into radiator however they are availabe from Rock AUto here: https://www.rockauto.com/dbphp/prt,107,61311378073
1 VOLVO 2 speed relay - as seen in the link - it's from 90's Volvo;s they were 9.95 each at picknpull in March 2013~ I snagged two and ONE WIRING LOOM / connectors to help it all go along
So far everything here is n line with the posts in the last 6 pages .
My biggest question was how to thread a metric 14mm temperature sensor (this one closes two circuits based on tempereature... 195 and 210 are triggers I believe) The thread above is the originator of this cool idea.....not me
NAPA did not have any threaded t-pieces that I could put inline with my 5/8 heater hose. HOWEVER by CHANCE I tried a NAPA 5/8 heater item that had a threaded connection and... it worked! Partt number 660-1414. It has 5/8 nipples and a thread that will work. AWESOME
So the BMW switch into the NAPA heater hose adapter creates TWO grounding opportunities for different temperature settings.
For me, both these grounding signals from the '0' pin can run to a (SPDT?) switch as in the original diagram, with a HIGH setting that automatically grounds the high if you will be winching while pumping tires with your compressor and stationary and just started the engine!, an OFF that turns it off for water crossings or simple desire, and a 'standard' setting that is automatic. Make sense?