02 Tahoe Electric Fan Conversion

[DrummerDude70]

Ok, so I know this subject has been talked to death, so I'll try to keep it short. Bought some factory fans from a ??? Silvi a few years back. Based on the number of blades, earlier than an '09. How do you test the fans for full operation before installing? I've hooked them straight up to a battery and they both turn on. Isn't one a higher speed than the other, or is that controlled in the ECM? Black Bear will do the tuning. TIA

 

[justirv]

Ok, so I know this subject has been talked to death, so I'll try to keep it short. Bought some factory fans from a ??? Silvi a few years back. Based on the number of blades, earlier than an '09. How do you test the fans for full operation before installing? I've hooked them straight up to a battery and they both turn on. Isn't one a higher speed than the other, or is that controlled in the ECM? Black Bear will do the tuning. TIA

You should purchase an appropriate fan harness, which normally would be from a 2005+ or in the case of an '02, from a 3rd party like Nelson performance (1-wire vs. 2-wire solution). The 3-relay harness of 2005+ will manipulate the ground trigger wire to put the fans in "series", halving the voltage and putting both fans on low speed. The ECM on 2005+ outputs a ground signal out of pin 33 and 42 (one of which is controlled by ECT and other by A/C signal, on the Blue and Red ECM connectors) to control fans.
Problem with an '02 (and earlier) is the ECM isn't capable of monitoring A/C pressure (no trinary switch), so typically (Nelson and others) will use the A/C clutch signal, which is a positive (+) voltage. There are ways to modify '02 ECM to include using EGR +5v ref, trinary switch, etc., but overly complicated. A Nelson 1-wire harness (or comparable) will be your easiest solution, using the A/C clutch signal, which will put 1 fan in high speed. I believe excessive ECT will activate both on high, depending on the harness (?). Check out thier website for explanation. I literally just completed my install a couple weeks ago. Check your Alternator output as well, stock maybe 105A, upgrade to 130A/145A recommended as these can pull over 500/600 watts. Hope that helps.

 

[DrummerDude70]

@justirv: Thanks for the info! Will definitely check into them. Actually, never heard of Nelson. Should have mentioned, mine is an '02 Z71, so alt is 135 amp. Another quick question: how do I identify what year the fans are?

 

[Fless]

Contact @ScottyBoy to see if he has any OE harnesses for sale.

And here's a thread to review, if you're interested:

I installed E-fans on my 2001

How-To: Installing 06 E-fans on a 2001 This is a step by step tutorial on how to upgrade any 00-02 Tahoe, Yukon, or Suburban to the 05-06 GMT800 electric cooling fans. This same setup can be used on 03-04 trucks as well, however the only difference is the wiring that connects to the PCM. I...

www.tahoeyukonforum.com

 

[justirv]

Contact @ScottyBoy to see if he has any OE harnesses for sale.

And here's a thread to review, if you're interested:

I installed E-fans on my 2001

How-To: Installing 06 E-fans on a 2001 This is a step by step tutorial on how to upgrade any 00-02 Tahoe, Yukon, or Suburban to the 05-06 GMT800 electric cooling fans. This same setup can be used on 03-04 trucks as well, however the only difference is the wiring that connects to the PCM. I...

www.tahoeyukonforum.com

Thanks @Fless !

 

[DrummerDude70]

Contact @ScottyBoy to see if he has any OE harnesses for sale.

And here's a thread to review, if you're interested:

I installed E-fans on my 2001

How-To: Installing 06 E-fans on a 2001 This is a step by step tutorial on how to upgrade any 00-02 Tahoe, Yukon, or Suburban to the 05-06 GMT800 electric cooling fans. This same setup can be used on 03-04 trucks as well, however the only difference is the wiring that connects to the PCM. I...

www.tahoeyukonforum.com

Fantastic! That's exactly what I needed. Thanks for the link/info. Cheers!

 

[ScottyBoy]

Yeah, I have several harnesses in stock right now. Shoot me a PM when you are ready to purchase. I accept PayPal and Zelle for payment.

 

[ScottyBoy]

You should purchase an appropriate fan harness, which normally would be from a 2005+ or in the case of an '02, from a 3rd party like Nelson performance (1-wire vs. 2-wire solution). The 3-relay harness of 2005+ will manipulate the ground trigger wire to put the fans in "series", halving the voltage and putting both fans on low speed. The ECM on 2005+ outputs a ground signal out of pin 33 and 42 (one of which is controlled by ECT and other by A/C signal, on the Blue and Red ECM connectors) to control fans.
Problem with an '02 (and earlier) is the ECM isn't capable of monitoring A/C pressure (no trinary switch), so typically (Nelson and others) will use the A/C clutch signal, which is a positive (+) voltage. There are ways to modify '02 ECM to include using EGR +5v ref, trinary switch, etc., but overly complicated. A Nelson 1-wire harness (or comparable) will be your easiest solution, using the A/C clutch signal, which will put 1 fan in high speed. I believe excessive ECT will activate both on high, depending on the harness (?). Check out thier website for explanation. I literally just completed my install a couple weeks ago. Check your Alternator output as well, stock maybe 105A, upgrade to 130A/145A recommended as these can pull over 500/600 watts. Hope that helps.

I sell refurbished OEM fan harnesses that I pull from 05 and 06 vehicles in the junkyard. Then I meticulously clean and inspect EVERY inch of the wiring in the harness and fan plugs, and the relay block. I scrub every bit of dirt, grease, and grime that I can. If I see any damage, I make an appropriate repair which in the case of a cut wires usually consists of soldering the wires back together and covering the repair in Marine grade heat shrink tubing. If its just the insulation thats damaged or nicked, then I cover the damaged area in Marine grade heat shrink tubing. Sometimes they have cracked or crushed Fan plugs, in which I end up de-pinning the wires and replacing the plug. Then I wrap the entire harness in new high temp wiring split-loom. By the time I'm done with it it's not only a standalone cooling fan harness, but its pretty much a brand new harness. Thats why I use the term "refurbished ". When I say I sell refurbished fan harnesses. And ANYONE who purchased one from can say that it would be VERY difficult to even tell it's a used harness by the time I'm done with it.
In the case of a 2000-02, I can modify the harness by soldering in an additional relay. ( I do charge an additional $25 to do this) That relay just changes the trigger polarity for the AC trigger from a negative trigger to a positive trigger. With a positive trigger wire, you can then splice into the AC compressor clutch wire and that will trigger your fan to turn on whenever the AC is running. This is exactly how I have mine hooked up on my 2001, and it's been working flawlessly since the day I installed it. How long ago was that? How about FOURTEEN years ago now? And I have the install thread on here to prove it. Just go search my old threads that I have posted on here.