ECU Controlled Fans - VA Binary or Trinary Switch

[lsuguy]

I am working through the wiring on my car and wanted to know if anyone had a wiring diagram for relays that are using the E38 ECU to control their fans with a vintage air trinary switch.

From what I have read you have to introduce a 3rd relay for the trinary trigger or the ECU will see it as a fault.

Appreciate the help!

[randy]

my gmpp unit has a ac trigger wire once i installed the pcm of nc fan bump and electric fan kit. after installing that i used a binary switch.

[cpd004]

I don't have a diagram, but have recently ordered a complete VA system. It is still all in the boxes. The rep did tell me a trinary switch was required for proper operation for an LS swapped car.

There's this generic video:

https://www.youtube.com/watch?v=l604JCZx_ow

And this link I had saved:

http://ls1tech.com/forums/conversions-hybrids/1808233-trinary-switch-ac-question.html

Not sure if any of these will help, because I'm not at this point yet myself. Let us know how it goes.

[lsuguy]

I have actually read through those same links and nobody offers a solution for the fact the ECU will read the negative trigger from the trinay switch as a fault.

Plenty of people say they add a 3rd relay but I cant seem to locate a wiring diagram for this scenario. I know how to get the fans to work using the negative (hi/low) trigger from the ECU but I can't figure out how to add the trinary switch into the mix....

[Z06vette]

I gave up trying to get the E38 to control twin fans. I used the entropy fan controller. It has has an AC trigger wire, and the dip switches let you easily set the on/off temps for each fan. I know this isnt exactly the answer to what you are asking, but its an option. Scott

[lsuguy]

I found this on a C10 truck forum. It appears that it will work but I am open to comments on this. Worst case is that the fans are powered by more than one relay under some circumstances but I don't think that should be a problem...

I have seen the entropy controller and its a nice setup.

http://i.imgur.com/XIpUdtF.jpg

[dhutton]

That will work fine. I did the same thing several years ago. I prefer the series/parallel low/high setup, but this will work, just a little noisier in low speed.

Don

[130fe]

my gmpp unit has a ac trigger wire once i installed the pcm of nc fan bump and electric fan kit. after installing that i used a binary switch.

I talked to a buddy of mine today (from camaros.net) that has that same setup and likes it a lot. If you have the GMPP harness, it seems like a nice way to go.

[randy]

I talked to a buddy of mine today (from camaros.net) that has that same setup and likes it a lot. If you have the GMPP harness, it seems like a nice way to go.
It was very simple and works like a charm. Cut a wire, add a wire, Run a wire or two, new relays and fuses in the fuse box and your done. Just like OEM.

[130fe]

Yeah I just bought the fan and bump kit last night. They have 10% off until tonight.

[randy]

Yeah I just bought the fan and bump kit last night. They have 10% off until tonight.

They want you to tap the ecu wire on the bump kit. Just tap it off of the fuse box since your already going to be in there. I thought it was going to be hard but man once you start you realize how easy it is. If you need some help just message me.

For the person that started this topic try not to overthink it like i did. I spent about a week trying to figure it out. eventually i just K.I.S.S and once i was done i just laughed how easy it was.