As said above, you can use HPTuners to turn the fan controls on in the ECM. This is an 05 Yukon (green/blue) ecm and 2002 Camaro fans wired up like a stock camaro, low is series, high is parallel. On low you can't hear the fans with the car running. Not sure what you're working on but the 02 fan shroud fit my chevelle radiator like it was made for it, just had to notch the top of the shroud for the upper hose outlet.
Wiring diagram I used,
https://lt1swap.com/2004vortec_pcm.htm
Blue 41 for fan 1
Green 33 for fan 2, both are ground triggers for the relay
https://drive.google.com/file/d/13WU...usp=drive_link
Wiring diagram for this setup:
https://ls1tech.com/forums/attachmen...pstnnu56hu.gif