JC8412

Great Write-up! Helped a ton

alex11

great info I did the install but It wasn't that clean but with this ill clean mine up for sure...

fastlsx463

"30-Blue trigger wire on OEM fan relay pack"

is this 30 on the relay the blue wire that goes to the #42 pcm signal wire?

Khipset

For those who need a little guidance on the Fan settings in HPTuners, I pulled this from a stock 2006 Silverado.

I would note that most of LR4/LM7 and L59's come stock with 186F thermostats. With external oil and transmission coolers, running engine temps of 185-190F is possible with even just one Fan on high. Please keep in mind the colder you keep the engine, your mileage decreases and you increase wear. If you're going to play with your temp settings, be sure to log your temps in different conditions and change your temps to meet your desires. Colder is not always better, especially on Daily Drivers.

bigmeex

Hello everyone so I have a 04silverado crew cab with a 5.3 I have all the things I need to hook everything up so if I cut the plug that gose to the side of the fuse box and put then to the pcm 33 is green and 42 is blue right and then I just have to do the tune is that right

Red_Beard

this is indeed an awesome tech write up, any thoughts to the '03 silverado with the 4.3?

1994Vmax

iTrader: (4)

Hook it up with the OEM harness just as its done on the 05 and newer 4.3 as well V8 trucks. You have the easy PCM to do as you can hook it up 100% factory install. Just get the OEM harness from a junkyard. And don't forget the two wire trigger connector that goes into the computer. Blue connector with the green wire on 42 and green connector with the blue wire on pin 33.

I have an 03, 04 and 05 and all are converted to efans using the gm harness. My trucks are 1500hds so regardless of year they had clutch fans..

Red_Beard

fan-tastic! LOL So, this harness...plug and play? then have the computer "switch" turned on for fan control? what fan assembly am i looking for? are our radiators the same? 4.3/v8?

k, another question...1994vmaz, i believe said connector GT-150 was the connector coming out from the pcm to connect to the plug that had the blue and green wire? if so, is this plug pig tail available to purchase thru gm?

and, shouldnt a TECH-2 be able to go in and give you the option to "flip" the fan switch(es) on?

thanks...

1994Vmax

iTrader: (4)

It is a GT 150 but I do not believe gm sells it in its own. Its in the main engine harness on an e fan truck so I imagine it would be sold only that way. The e fan harness is built in the front lighting harness but once you peel the jacket off its a separate loomed harness ran in the same tubing as the lighting harness. Honestly I would just see if you can strip an e fan truck yourself somewhere in a wrecking yard. If not the actual e fan and lighting harness is less than 200 bucks and you can go to waytek wire as an example and buy the connector and pins you need for a trigger harness.

Your rad will be the little 28 inch one so no you need the 34 inch wide one if you want the factory fans. My HD trucks a have the 34 so its a non issue for me but for older half tons for the most part you need the rad too. And the factory e fans attach with 2 boots identical to your radiator bolts... the ones attaching your fan shroud are not the same.

Tech II is useless for this exercise. You need a custom tuning software to enable the fan outputs on the pcm as well as set your temperatures/ speeds and cycling pressures with the a/c. I just copy pasted an 05 e fan trucks fan settings and modified the temps for something closer to the factory 186 degree t stat as they are otherwise set quite high. I'm not sure if the 4.3 uses a 186 or a 195 degree t stat like the old 350s did. That's up to you lol.

GMCtrk

iTrader: (27)

Bumping this back up because I'm about to make the jump to OEM electric fans.

I just wanted to point out that the 99-02 PCM CAN solely control the electric fans.

I had LS1 efans several years ago on the 1 pin harness which utilized the A/C trigger wire for the second fan. This method is downright stupid, in my opinion and I wouldn't recommend it to anyone. Not only is the fan switching on and off every single time your a/c compressor cycles, but the second fan isn't necessarily even required when the a/c is on. All of this is terrible on the electrical system.



Does anyone know if the OEM 05+ harness can be used with the 2 pin method on 99-02 PCM?


Pin 42 - empty - Fan 1 Control - This will be empty on 99-2002 harnesses. A pin can be added for electric fan control. Programming will enable the fan control. PCM supplies a GROUND to turn on a relay. If you have two fans, keep reading, pin for fan 2 will be on the RED connector C2. You must wire your fans through a relay.

Pin 33 - Dk Green - Fan 2 Control - some 99-02 harnesses will have a pin here, this was used for the HVAC Recirculation Door control. The PCM would control the A/C recirculation to help cool the a/c system if it got too hot. In an engine swap, programming can be changed to let this control a second cooling fan. Again, PCM supplies a GROUND to run on a relay. You must wire your fans through a relay.