Aux AC Fan for 99 5.7 Tahoe - Wiring?

[Kran]

i see there is a provision on the pcm for an aux fan which i believe was used for the 7.4 trucks. is this pin enabled for 5.7? does it trigger on with 12v and can be used for a standard relay? trying to think how to properly wire an aux fan for the condenser. trying to avoid pcm tuning. i know i can just use the ac clutch engagement for relay trigger but i'd like other ideas.

 

[1998_K1500_Sub]

What year vehicle?

1996+ will require a “tune” to enable aux fan operation, the installation of an additional wire/pin in the ECU harness, and an external “standard” relay; that’s how it was wired from the factory. I’ve done this.

I’m not sure how the fan was powered / controlled in 1995 and earlier years.

An alternative would be to wire it using your own design. @Frank Enstein has posted on this topic.

See also this thread:
https://www.gmt400.com/threads/fan-clutch-staying-locked-on.57440/post-1232391