How would you wire up the cooling fan relay with an aftermarket ecm? I am using the factory fan relay and want the cooling fans to work as close to factory as possible. On and off with the ecm and then on when the a/c is on.

 

Most aftermarket ones have 1 or 2 negative ground triggers to activate relays-and, you should be able to change the temp sensor input data to change the temps at which the outputs ground. Ac use should ideally be determined via a trinary circuit but that adds to the cost and complexity a bit to your fan harness but at least with a properly integrated trinary circuit, fans won't need to be on if for example you are cruising down the highway with the AC on because you should have sufficient airflow through the condensor to keep high side pressure under 235 psi.

A trinary circuit added to a fan harness kit can add as much as $100 to a fan harness. A well designed cooling fan system is more than a switch and a relay.

 

I am trying to get close to that setup. Right now I have the ECM output which is negative to the OEM fan relay input. Here is a crude drawing of the factory setup. Right now when I have the brown connected and not the ecm the fans turn on when I turn the key. When the ecm is connected it does nothing and it says the fans are on??
Where can I buy this kind of fan control?

 

I would need to know the outputs of the ecm you're running for fan control. Not sure why your brown wire would engage the fan with the ecm disconnected. IMO, I would opt for a standalone electric fan control and deactivate the ecm fan outputs but that's me.