Good afternoon, I have a question about the LS1 dual fan setup and how to wire them to have low & high speed functionality

Currently I have them to run both at the same time, high speed when the car reaches around 225 degrees (aftermarket fan controller from parts store)
The amp draw from both fans turning on at full speed draws power from the cars electric system heavily and is noticeable with a slight hesistation/bog

I would like to run a 3 relay setup, like this below

relay 1 will run both fans in series, so 6v each (I'm not sure if I will have them run 6v on ignition or use a 2nd temperature sensor for low temp mode)

then relay 2 & 3 will run the fans in parallel so 12v each when the fan temperature switch triggers/grounds itself

BUT I'm not sure how to cut the 6v connection when relay 2&3 trigger?

I believe this is normally done with the PCM/ECU on the 4th gens, etc...


How did you guys wire your low/high speed setups?

 

Power relay 1 from the normally closed terminal of relay 2 or 3. When that relay engages, it will disconnect relay 1.

 

gotcha, thank you! sounds simple

Not super familiar with relays so I start to second guess myself haha.

 

Here are a couple diagrams for you. The first is the stock LS1 dual fan wiring. The second diagram achieves the same end result, but with upgraded wire and fuse sizes. In either case, you will need 2 trigger wires - 1 for low mode operation and 1 for high mode operation. The trigger wire should go to ground when enabled. I recommend your fuses be located in the engine bay and come right off your battery. Both of these diagrams were originally made for LS swaps, but so long as you implement the relays and wiring with appropriate triggers, it will work the same.



Factory LS1 Fans




LS1 Style Fans with Upgraded Fuses and Wire

 

Thank you, this is perfect

 

I dont know if it can be used on a thirdgen but theres a website that builds harnesses just for LS fans I beleive

www.ls1fans.com

 

Racetronix also makes a really nice upgraded fan harness.