How To: '99-'04 GMT800 OEM E-fan upgrade
- Thread starter ScottyBoy
- Start date
Carolinaboy
Full Access Member
Don't have a GM but still a great write-up it makes it seem pretty simple 
ScottyBoy
No, that's not a banana in my pants.
Don't have a GM but still a great write-up it makes it seem pretty simple
It is pretty simple. The harness actually only has 4 connections, the battery, Ground, the PCM trigger wire, and the AC trigger wire. The extra relay I wired in for the AC wire only has 1 additional ground wire that needs to be hooked up in addition to the 4 connections I just mentioned. The hardest part is simply routing and securing the wiring.
Chevyman
Full Access Member
Nice write up Scotty. I will be using this soon to install my e-fans.
ScottyBoy
No, that's not a banana in my pants.
I also want to add that my AC is blowing much colder with these fans. Even when it got up to 107 the other day, my AC was blowing ice cold even at idle.
But I am seeing one downside. These fans draw a LOT of current. The relay block even has 40 amp fuses on each fan. When both fans are on at idle, my voltage guage drops from 14 down to 12. I need to find a higher amperage alternator, or maybe a smaller pulley for mine. Justin suggested against the pulley though and suggested I go straight to a bigger alternator. Especially considering I have power everything in my truck, and the rear AC as well. If the rear AC is off, it doesn't drop all the way to 12 volts.
But I am seeing one downside. These fans draw a LOT of current. The relay block even has 40 amp fuses on each fan. When both fans are on at idle, my voltage guage drops from 14 down to 12. I need to find a higher amperage alternator, or maybe a smaller pulley for mine. Justin suggested against the pulley though and suggested I go straight to a bigger alternator. Especially considering I have power everything in my truck, and the rear AC as well. If the rear AC is off, it doesn't drop all the way to 12 volts.
A nice cammed 6.0 should do the trick! 
Great job, Scott.
On my list of 'hoe mods.
On my list of 'hoe mods.
I thought about it but there's something about knowing my cooling isn't being handled by electric motors and electric fans that weren't stock that bugs me. One simple failure could strand me.
The HP gains can't really be that great anyway, can they?
The HP gains can't really be that great anyway, can they?
15 HP on a hard pull would be noticable
Nice writeup Scotty.
I'm thinking of doing this to my 02. Just need to get everything. How can you tell if you have the smaller alternator and will the alternator off an 05 or 06 that you get the fans off work?
If you look really close, you will see either "105A" or "130A" engraved on the case of the Alternator.
Here is where the 130A is engraved on mine.
The 05-06 trucks came with 145 amp alternators. But the plugs are different. Im not sure what year they changed the plugs.
Does anyone know if ours can be rebuilt and beefed up to 145 amps? I want to say there was an individual on here that their dad has an alternator repair shop. I just checked mine and it is a 105 amp so the fan swap would not do me well until I get a bigger alternator.
