PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

P01 Dual Electric Fan Conversion and Configuration

Thread Tools
 
Search this Thread
 
Old Aug 24, 2025 | 09:22 AM
  #1  
brokedadbuilds's Avatar
Thread Starter
Teching In
 
Joined: Apr 2025
Posts: 3
Likes: 1
Default P01 Dual Electric Fan Conversion and Configuration

There are lots of videos and resouces out on the interwebs about this, but I wanted to do a quick write up about it since it may be more helpful than a video. I am sharing what I did with my setup and how I did it so to each is own and your miles may vary but this is pretty much the same with aftermarket fans. This is just ging to cover the Fan setup without AC. Depenging on the PCM you will have more parameters to adjust for the AC settings with electric fans. I have a P01 PCM so there are not as many parameters to change and currently im not running AC.

Also a video about it where I go over it can be found here. I am not expert though...just a guy learning stuff as I work on my own LS build.


Hard Parts:
  1. Dual Electric fans from a 2000's Escalade or Denali from a junk yard and the fan relay fuse box that is attached to the engine compartment fuse box. Pic of what the fuse box looks like is below.
Get the entire fuse box, harness and the fans as you will use the green and blue wire from the fan fuse/relay box harness for the ground wires to go the the PCM for controlling the fans

Setting it Up:
  1. Mount your electric fans and hook up your harnes and route it so that you can attach the fan fuse/relay to the right side of the engine fuse box. There will be a provision on the engine fuse box that it will slide in place.
  2. On your PCM there will be two pins that you will be focusing on to wire up the trigger wires for Fan 1 and Fan 2. The Green Wire for Fan 2 will go to Pin 33 on the Blue Connector and the Blue Wire for Fan 1 will go to Pin 42 for the Red Connector
  3. You can run the wires directly to the PCM connector since the entire circuit is already fused from the fan fuse/relay box and these are ground control side wires.
  4. You can go to LT1swap.com and find the wiring diagrams there to help you further if you want.

Electric Fan Fuse/Relay box and harness






Programming:

I use PCM Patcher and TunerPro so if you are using HP Tuners the settings will be similar. This example I am using PCM Patcher.
  1. After you connect to your PCM and download the BIN file using PCM Hammer and open it in PCM Patcher search for "recirculate" or "recirc" in the search bar or just find the Vehicle System folder
  2. Within the folder you will see the parameter for Auto Recirculation or Recirculation Door. This will be checked by default so that the PCM controls the recirculation door automatically but when you uncheck it the PCM uses it for Fan 2 control.
  3. After you save the changes made to the recirculation door parameter go to the Fans folder within the Vehicle Systems section.
  4. You can select the the Fans folder and it will show all the parameters associated with Fan 1 and Fan 2 control.
  5. You can mirror the parameters I have in the screenshot as a starting point. I have my Fan 1 come on at 185 degrees since during the summer in the south it gets really hot here and I want to ensure the engine stays below 190 degrees.
  6. For the Fan 1 and Fan 2 low and high thresholds be mindful to only have about 5 degree difference for the fan 1 low and high and the Fan 2 low and high.
  7. Ensure that you have the Fan type parameter set to series parallel for dual fans
  8. Remember to set your vehicle speed low and high correctly as well. You want to ensure that you set your fans to turn off at higher speed as they will not be needed due to ram air flowign though the radiator.
  9. once you save your parameters save the Bin file as something that helps you know it has the Fan changes and write it to the PCM with PCM Hammer.
  10. Start up the vehicle and let it get to the operating temp for Fan 1 to turn on and once it does your good to go!
Auto Recirculation Parameter:



Fan Control Paramters:

Reply
Old Aug 24, 2025 | 07:31 PM
  #2  
Fast355's Avatar
TECH Resident
15 Year Member
Liked
Loved
Community Favorite
 
Joined: Oct 2006
Posts: 993
Likes: 173
From: Euless, TX
Default

Originally Posted by brokedadbuilds

Programming:

I use PCM Patcher and TunerPro so if you are using HP Tuners the settings will be similar. This example I am using PCM Patcher.
  1. After you connect to your PCM and download the BIN file using PCM Hammer and open it in PCM Patcher search for "recirculate" or "recirc" in the search bar or just find the Vehicle System folder
  2. Within the folder you will see the parameter for Auto Recirculation or Recirculation Door. This will be checked by default so that the PCM controls the recirculation door automatically but when you uncheck it the PCM uses it for Fan 2 control.
  3. After you save the changes made to the recirculation door parameter go to the Fans folder within the Vehicle Systems section.
  4. You can select the the Fans folder and it will show all the parameters associated with Fan 1 and Fan 2 control.
  5. You can mirror the parameters I have in the screenshot as a starting point. I have my Fan 1 come on at 185 degrees since during the summer in the south it gets really hot here and I want to ensure the engine stays below 190 degrees.
  6. For the Fan 1 and Fan 2 low and high thresholds be mindful to only have about 5 degree difference for the fan 1 low and high and the Fan 2 low and high.
  7. Ensure that you have the Fan type parameter set to series parallel for dual fans
  8. Remember to set your vehicle speed low and high correctly as well. You want to ensure that you set your fans to turn off at higher speed as they will not be needed due to ram air flowign though the radiator.
  9. once you save your parameters save the Bin file as something that helps you know it has the Fan changes and write it to the PCM with PCM Hammer.
  10. Start up the vehicle and let it get to the operating temp for Fan 1 to turn on and once it does your good to go!
Since you are talking E-Fan conversion and it is pretty generic information.

Early truck OS often do not have the full fan code in them. I usually use a 2002 OS for all conversions. The 2002+ code allows for the ac pressure transducer to be enabled to properly control dual speed fans when using AC.

I have run into vehicles that ram air alone even at 70-75 mph will not keep them cool. In most cases enabling the fans to run cools them down to an acceptible temperature but not always. I had one that I had to go back to the clutch fan on to keep it cool prior to making changes to the cooling stack by adding factory GM air guides and improvising an extension under the factory air dam (more on that below). Since it was P59 run I went back with an EV clutch that is PCM controlled. That was the best of both worlds. You could control the mechanical fan to mimize power loss yet still have full cooling capacity on demand. The P59 fan code for the EV clutch has tables to control the fan for engine temp, transmission temp and ac pressure.

On my Express van I ended up adding the air guides GM put on the newer vans that bolt to the condenser and help funnel all the airflow from the grille opening through the cooling stack. That helped the cooling considerably vs allowing a lot of that air to flow around the cooling stack through the core support openings behind the headlights. Adding a 3" tall strip of PVC patio/sidwalk edging below the factory air dam also considerably improved the cooling by helping create more negative pressure under the van to help draw airflow through the cooling stack. The result of those changes is I went from almost always needing a powerful fan functioning to rarely needing a fan at all over ~50 mph.
Reply
Old Aug 25, 2025 | 07:43 AM
  #3  
brokedadbuilds's Avatar
Thread Starter
Teching In
 
Joined: Apr 2025
Posts: 3
Likes: 1
Default

Nice additional info to add to it! Each use case will be different but the more info to share the better!
Reply




All times are GMT -5. The time now is 02:44 AM.

story-0
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?

Slideshow: We take a close look at the ONE and Artidiag 800BT2 diagnostic tools from Topdon and the reasons to buy one over the other.

By Pouria Savadkouei | 2026-05-28 11:05:11


VIEW MORE
story-1
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine

Slideshow: The controversial Ferrari F6 swaps its original flat-12 for a Corvette Z06-derived LT4 V8 and sends power to four rear wheels through a custom-built drivetrain.

By Verdad Gallardo | 2026-05-26 18:23:54


VIEW MORE
story-2
7 Most Reliable High-Performance Engines GM Has Ever Built

Slideshow:These GM engines didn't just make huge power, they survived abuse, boost, track days, and six-digit mileage with a reputation for refusing to quit.

By Verdad Gallardo | 2026-05-21 16:45:27


VIEW MORE
story-3
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-4
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-5
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-6
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-7
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-8
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-9
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE