Question: LS3 fan control wire; power or ground?

[Gmachine1911]

Originally Posted by randy

Binary switch

All the wiring is inside the fuse box. You don’t need to touch any connectors. When you get the kit and your ready to start the wiring I will walk you thru it since I still have my instructions.

Bottom line is you have two wires going to the one relay. I think blue and green. You cut one and then reroute it to your new relay. You give that relay some power, fuse it, and add a line out. Now your fuse box has two line outs. The wire that you tap into for the AC bump you are already working with the new dual fan kit. Tap into it at the fuse box and some other wires. Trust me it’s really easy once you start messing with it.

When you get the kit just text me at 972-814-8824. Maybe when I have some free time I’ll dig my instructions out and just make a diagram for you

I appreciate that more than you know! You're a scholar and a gentleman I've over-thought it to the point where this whole fan thing has me psyched out (which is why I'm just now doing it). I've still got the binary switch that came with my VA kit so I'll dig it up to have at the ready.

[randy]

Confirm the original fan relay is in the right location based on the pcm diagram. My buddy has one where his fuel pump and fan relay were in the opposite location.

- Blue and green 18g wire going to pin A9 in the fuse block. Cut only the blue wire going to pin A9.
- Crimp the supplied blue wire to the fuse block blue wire feed ( read the entire thing before doing this crimp. It will make sense in a few min).
- Tape off the blue wire other end that was connected to the green wire going into A9
- Install one blue pin in slot C4 and install the other blue pin in D3.
- Install the red 12g wire between pins c6 and m3. The pins are different and the wider one goes in m3
- Install orange 18g wire Y harness in d6, l6, and c1
- Install white 12g wire in slots d4 and d2. it doesnt matter which goes where
- install the black 12g wire in d1
- install the brown 12g wire in c3
- add the supplied 10amp and 40 amp fuses into the corresponding spots to l6 and m3.
- install the relays

- now you are ready to wire the fans.
- the original blue wire in the kit will go to fan 1 positive
- The new brown 12g wire will go to fan #1 neg
- The new white 12g wire will go to fan #2 positive
- The new black 12g wire will go to fan #2 neg.
- i would highly suggest you get some 12g blue, brown, white and black wire so you can make your own harness from the fuse box to the fans. Keep the same color really helps the entire way.
- now just upload the new tune and your good. You can still run the car without the new fan patch till you get it figured out. I did for over a year and no issues.

with the ac bump this is what i did

- Ground the black wire
- The light blue wire goes to the compressor clutch wire. Get some long light blue wire and route this the entire way up front with your dual fan brown, white, black, and blue wire.
- now to the green and blue wire they want you to spice by your ecu into the pins. Dont do that. Here is a cleaner way. Remember earlier you just clipped the blue wire from the green wire and rerouted the blue? Well now You need to work with those wires again.
- the green wire needs to splice into the green wire earlier which was going to pin A9.
- The blue wire which you may or may not have crimped earlier that WAS going to A9 that you rerouted to C4 and D3 well the blue wire from the ac bump taps into that wire.
- Now you see why the ac bump is easy to do the same time you are installing the gmpp dual fan kit. You are already messing with the two wires from the ecu but at the fuse box. The rest are just signal, power, and ground wires.

[Gmachine1911]

Gotcha...so I basically don't have to splice into the ECM connectors...that's awesome! It's against my religion to cut up a perfectly good wiring harness!

[randy]

yup. those wires just route to the fuse box so just tap them at the fuse box since you are already messing with them there.

[130fe]

I am glad you posted this up Randy. I am with Shane in not wanting cut my pcm connector wires (plus the fact that my pcm is hidden inside the passenger fender). I have both of the PCMofNC kits (fan and AC bump) sitting in a box in my garage. Been running the Entropy fan controller for the past couple of years but wished you were able to input a VSS signal in (so your fans aren’t running on the highway. Looks like I have found my pre Christmas project after I get my car back next week (getting T56 Magnum and Holley mount system put in).

[NAPA 68]

Great thread and thanks for posting. One of the few things I am not happy with on my LS3 conversion is the GMPP fan control strategy. The seem to always be on at a stop light.

Tim