augiedoggy

aluminum or brass doesnt matter all metal should conduct the ground in this application just fine. My bet is a bet switch or something isnt wired correctly. If the fans come on if you ground the single wire going to the switch then its a bad switch. If not then something else is wrong.

Big Block Dave

My understanding is that with these single wire switches, if you use (excess) Teflon tape for a sealant it won’t ground properly.

I bought a two wire switch to avoid any grounding issues

Richard454

There are several ways to wire-

I like using a PWM controller -

1. Has soft start- doesn't go full boogie on your battery/charging system as it slowly starts the fans up
2. It varies the speed of the fans as needed- not on- off- on...
3. Own temp sensor to control then fans
4. Has a over ride switch- turn on the fans full speed with the flick of a switch ( AC)
5. Made in USA!!!

https://www.summitracing.com/parts/der-16796






The teflon tape story isn't really a problem-

http://www.stl-vettes.com/65Vette/co..._and_Gauge.pdf

Big Block Dave

interesting! Thanks

talentscout

Thanks BB Dave, do you have a part number and or pic of your two wire sending unit?

Big Block Dave

https://www.summitracing.com/parts/p...iABEgL-O_D_BwE