Originally Posted by
Chris Barker
**UPDATE**
So for MY tahoe, I had wired the trigger wires as shown in the diagram in my first post, green wire to pin # 43 on blue ecm connector, blue wire tapped to pin # 33 on red ecm connector, I do not recommend tapping # 33 on the red connector as it puts out a 12V + signal, the fans use a Ground Signal.
I ended up disconnecting my blue trigger wire, tapping into the a/c compressor engage wire and using a relay wired with negative polarity to trigger the #2 ( Blue ) Trigger Wire to kick fans on high when the a/c is engaged..
I was having some issues with the fans staying on after the key was turned off, and finally had gotten that issue fixed, but today, my RECIRCULATION actuator started click non-stop.. That is the reason I started looking at the wiring again.. I don't know if having it hooked up to the #33 pin caused the actuator to start acting up, or if its just old and started giving out finally, I mean my tahoe does have 230,000 miles on it now.. But now I have to remove the top piece of the dash to get to the actuator, for now, as long as I leave the recirculation button engaged, it stops clicking. So it will have to just stay that way for a little while until I get the time to change it out.