The OEM fan harness hooks to your ECU with two wires.
The ECU will turn the fans to the correct mode when needed.
Temp and ac.
You will need a 05-06 radiator for that ebay kit.
Also via a tune, turn on the OEM fan control.
Cost will be aProx what a flex lite kit would cost. But, you get OEM fan control and all the perks with it. The biggest bonus is the noise level. OEM is quiet. Flexlites or aftermarket universal fans are loud as hell.
When i had my flexlites, i had to turn off the vehicle at food drive throughs.
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If you go pure aftermarket. Hayden temp sensors are the best.
Use two of them, one for each fan.
Then tap into the relay trigger for fan #2, with the AC clutch wire.
You will need a diode to keep the temp sensor and AC clutch from cross talking at the wrong time.
Example.
You have two fans and temp sensors wired independently from each other.
Fan one turn on temp 180.
Fan two turn on temp 225.
Fan two relay is wired to AC clutch, no diode.
Normal operation,
Fan one cools engine.
Fan two turns on with AC clutch cycle.
Your engine begins to over heat and hits 225.
Fan two temp sensor tells fan two to turn on, while also sending 12volt signal to AC clutch.
But you, was smart and decided to turn off AC to reduce load on the engine, in attempt to help cool the engine down.
But it doesnt work, there is no diode on the AC clutch trigger wire for relay two.
This forces the AC clutch to engauge negating your command to turn the AC off.
So if you want to do it, do it right.
And hope all of these systems with the aftermarket setup doesnt fail.
OEM setups dont fail. This os the reason it sells for the cost it does.