I installed E-fans on my 2001

[Burban22]

I’ve successfully swapped my ‘03 burb to efans thanks to this thread and @ScottyBoy!

For those of you that have a 2003 or 2004 GmT800 this is how I swapped mine. 2005 and up should already have efans.

You’ll need a tuner to enable electric fan controls in the engine computer. I had mine tuned a few years ago and they hand enabled electric fan control.

You will also need two ECM plug pins. Pull from junkyard ECM plug or acquire online. I just crimped them to the junkyard fan harness.

At the junkyard, I pulled the entire front harness out of a 2005 Yukon XL. I could’ve just stripped the fan harness there, but I just pulled the whole thing.

Here is what the fan harness will look like stripped away. Also make sure you grab the little fuse box for the fans.

The blue wire goes to the green computer connector pin 33.

The green wire goes to the blue computer connector pen 42.

I then ran the fan harness alongside the original front harness. Should’ve put the plastic tubing on before I did this but here it is.

I landed the positive wire for the fan harness here. This is 12 V from the battery all the time regardless of key on or off. This allows the fans to turn on automatically if needed when engine is hot and shut off.

Here’s the wire loom installed and zip-tied.

Found some rodent damage I didn’t have any of the liquid electrical tape and ran out of normal electrical tape so I just use some brown duct tape I had. It will be covered under the fuse box cover anyway. Maybe the mice won’t like the extra stickiness and fabric of this tape lol

The fuse box and relays for the electric fans fit right next to the main fuse box. I just had to remove a plug that was blocking the alignment slider.

The ground wire I just sandwiched between the metal bumper bracket and frame horn. I’ll go back and put a bolt through it but it’s super tight and seems to work fine.

All finished, much more room between the fans and engine versus the mechanical set up.

No, I don’t have a 6.0, just scored the engine cover at the local pick and pull.

 

[Matthew Jeschke]

Wow thanks for sharing. Curious what year vehicle did you score the fans from?

 

[Burban22]

@Matthew Jeschke I grabbed the fans and the harness from a 2005 Yukon XL

 

[Matthew Jeschke]

Welp, I can say I blew up the eFan circuit. Long story short, GM didn't design the circuit to handle the eFans in high speed mode for extended periods of time. Especially with the larger 6.2L fans from GMT900. I went through the design for the GMT900 and there's not much more to it than the GMT800. It melted my relays, burnt the contactor in the relays, stuck open.

Word to the wise, be careful with the high speed fan. The circuitry isn't designed to hold it on for extended periods of time, especially if you have the heavy duty fans from the 6.2L

Backstory: I have a built 6.0L, which produces more heat. It should be fine though, as the same circuitry is used on 6.0L GMT800, and similar with GMT900 (relays are the same and fuse ratings). However, I switched from a 195F t-stat to a 180F t-stat. The radiator seems to be a bit too small for 180F... The tuner I'm working with commanded the fans on earlier too. This combination created a scenario where the high temp fan runs permanently every time I run the truck. It caused the two fan relays to overheat and fail.

 

[LsHart]

Yeah, they sell a wiring kit for the e-fan setup. Just a few wires to connect.

Takes it and makes it stand alone.

 

[Matthew Jeschke]

What is the kit called? I may have to look into it?

 

[LsHart]

40 bucks on parts geek.

 

[Matthew Jeschke]

Ah yes I have seen these. I used a factory box with PCM control.

Have you used one of those harnesses? Do they work well?

 

[Roilux]

I’ve successfully swapped my ‘03 burb to efans thanks to this thread and @ScottyBoy!

Ooof, I needed to see this. My setup to add efans and a harness from @ScottyBoy has been sitting on a shelf for too long. It's time to get off my duff.

I see an auxiliary battery tray in your photo. Plan to add a second battery in the future?

 

[Tonyrodz]

Ooof, I needed to see this. My setup to add efans and a harness from @ScottyBoy has been sitting on a shelf for too long. It's time to get off my duff.

I see an auxiliary battery tray in your photo. Plan to add a second battery in the future?

Really easy job. @ScottyBoy has everything labeled. Everything is plug n play.

 

[Roilux]

Really easy job. @ScottyBoy has everything labeled. Everything is plug n play.

Ok ok ok. This week it is. **grabs laptop with HP Tuners & fan settings**

 

[Doubeleive]

anything that takes the load off the factory wiring will work, a couple heavy duty relays wires directly to the battery, grounded on the frame and to the fans, the factory harness would then just be the trigger. I have done this multiple times with HID lighting because they cause the same damage.. melted fuses, melted relays, melted wires.

 

[Spaul]

40 bucks on parts geek.

I see the two trigger wires does it come with the schematic/diagram for low and high trigger wires?

 

[LsHart]

Yes

 

[LsHart]

Comes with a little book I think. Lol

 

[Burban22]

Ooof, I needed to see this. My setup to add efans and a harness from @ScottyBoy has been sitting on a shelf for too long. It's time to get off my duff.

I see an auxiliary battery tray in your photo. Plan to add a second battery in the future?

I was going to add a second battery but haven’t needed to since the new Sam’s Club battery has been just fine.

 

[Roilux]

I was going to add a second battery but haven’t needed to since the new Sam’s Club battery has been just fine.

I added a tray to move the jack, hitch and oddities up front that are normally stored in the back jack storage space. I'm still looking for an appropriate sized box to button it up.

 

[Roilux]

Really easy job. @ScottyBoy has everything labeled. Everything is plug n play.

Mission accomplished although that frickin' big nut had me cussing in cursive.

I did not have a slick articulated wrench that attaches to an impact driver. I also refuse to beat on an engine with a dead blow hammer as sooooo many Youtube videos suggested. Leverage and two cheater bars prevailed.

Look at all this space! Special hanks to @ScottyBoy for preparing the OEM harness. It is flawless.

 

[Tonyrodz]

Mission accomplished although that frickin' big nut had me cussing in cursive.

I did not have a slick articulated wrench that attaches to an impact driver. I also refuse to beat on an engine with a dead blow hammer as sooooo many Youtube videos suggested. Leverage and two cheater bars prevailed.

Look at all this space! Special hanks to @ScottyBoy for preparing the OEM harness. It is flawless.

I forgot about removing the fan. That is the biggest pita about the whole job. Where'd you place the small electrical box with the fan relays? I'm not happy where I placed mine.

 

[Roilux]

I forgot about removing the fan. That is the biggest pita about the whole job. Where'd you place the small electrical box with the fan relays? I'm not happy where I placed mine.

I fought that nut for a good minute then made use of the bar the came with the 36mm wrench. Secured the bar to the pulley with a nut and bolt and added two cheater bars to break the nut free with a two man effort. It was that tight. Stupid tight. No reason to be that tight.

Fan relays were placed to the right of the fuse box where they reside for '05-'06 years. When I pulled the fans from PYP the fuse box was included that has the inspection cover for the relays. It all snapped together easily.