Nelson LS1 Fan Harness Problem

[farmtruc]

There is no reason a PCM can't be set up to run the pins 33 and 42 correctly and use the correct harness design .

Yes there is, (with this harness), on some truck pinouts that pin is already taken, I can't remember exactly what its connected to, but you can't tap into it or replace it.
On some trucks you can use the pcm for the a/c, however, the pcm needs to support that, like on an fbody or like the '05+ trucks are setup.

I'm sure a harness can be designed to work with anything, but not with this setup/harness (what he has). So, that's what we have to fix.

Oh, I just looked it, pin33 "recirculation door control", can't use it!

[Chevy366]

Yes there is, (with this harness), on some truck pinouts that pin is already taken, I can't remember exactly what its connected to, but you can't tap into it or replace it.
On some trucks you can use the pcm for the a/c, however, the pcm needs to support that, like on an fbody or like the '05+ trucks are setup.

I'm sure a harness can be designed to work with anything, but not with this setup/harness (what he has). So, that's what we have to fix.

Oh, I just looked it, pin33 "recirculation door control", can't use it!

As Red said 4 relays can do it .
Perhaps I look at things differently than that , I think 2002 up can be wired to use 33 and 42 , some use pin 16 for fans (red connector , green 33) . Can you look at pin 16 and see if it will work ?
Funny that pin 33 will not work in some , cause all you need is PCM to ground the wire , can a segment swap be done with just the needed fan parameters ?
I agree that fans need to be on when A/C pressure reaches critical pressure , keeps it from going boom .