chpspecial Posted April 16, 2007 Report Share Posted April 16, 2007 i've been trying forever to find out how to put my 05 factory e fans on a manual switch. anybody got an idea for that? I havent done this but, If you ground one of the pins on the first relay, tha fans will come on. So if you where to put a switch on that pin, you could have your fans on when ever you want. even when the truck is shut off. I will look into wich pin it is later today and update. I found out when I was playing with a test light that this works. Link to comment Share on other sites More sharing options...
wody Posted April 16, 2007 Report Share Posted April 16, 2007 Do you want to disconnect them from the computer all together and only run them with the switch, or are you wanting to control them in conjunction with the computer? yes in conjunction with Link to comment Share on other sites More sharing options...
EmergencyVP1 Posted April 16, 2007 Report Share Posted April 16, 2007 chp has a good idea, but I wonder what would happen (if anything) if you had your manual switch on and the computer sent tried turning the fans on also...Would this throw a code ?? Link to comment Share on other sites More sharing options...
wody Posted April 16, 2007 Report Share Posted April 16, 2007 chp has a good idea, but I wonder what would happen (if anything) if you had your manual switch on and the computer sent tried turning the fans on also...Would this throw a code ?? that is exactly my delima. i know electrical can get complicated when grounds and powers start to feed back. Link to comment Share on other sites More sharing options...
ccgoodwrench Posted April 17, 2007 Report Share Posted April 17, 2007 I havent done this but, If you ground one of the pins on the first relay, tha fans will come on. So if you where to put a switch on that pin, you could have your fans on when ever you want. even when the truck is shut off. I will look into wich pin it is later today and update. I found out when I was playing with a test light that this works. that's what the PCM is doing, it grounds the relays when the set point temp is reach. their is a harness that connects to the fuse box it is part no 15216042 FWD lamp harness. Link to comment Share on other sites More sharing options...
chpspecial Posted April 17, 2007 Report Share Posted April 17, 2007 It shouldn't matter since the teh fan harness will just be receiving a ground signal twice, which I dont think will be a problem. It it was positive, then it would cause a problem. Link to comment Share on other sites More sharing options...
chpspecial Posted April 17, 2007 Report Share Posted April 17, 2007 If you have a nelson harness, the first relay closest to the 'Y' in the wireing harness there is a blue wire that is smaller than the rest, it is pin 85, if you ground it, the fans will come on at any time. Link to comment Share on other sites More sharing options...
CoolBlueSS Posted April 17, 2007 Report Share Posted April 17, 2007 Mr. P, If you are using the defrost or AC, then one fan turns on high...If the engine reaches the preset rate with AC or defrost on, then both fans come on..If AC is off and engine reaches temp, then one fan turns on low....It's a 3 relay system, mount relays on the cover of the PCM, plug the fans in, insert wire into pcm connector and tap into the harness next to the alternator, and your done... I just want to be clear on this, they will work with the AC on an 03, correct? I'm not too concerned with dual speed as much as I am running when the compressor kicks on. Link to comment Share on other sites More sharing options...
chpspecial Posted April 18, 2007 Report Share Posted April 18, 2007 Yes the three relay harness will alow the fans to kick on when ever the A/C clutch engages. Link to comment Share on other sites More sharing options...
ccgoodwrench Posted April 29, 2007 Report Share Posted April 29, 2007 The factory harness isn't using any relays for the AC, Their is a table in HPtuners that adjust air flow at idle, it is in the dynamatic aiflow. I was told to set the fan 1 to .10 gsec and fan 2 to .20 gsec. This compensates for load on engine (alt). For some reason GM did not have the fans come on with the AC request. Sombody can correct me if I'm wrong. Link to comment Share on other sites More sharing options...
wwd_mbtch Posted June 26, 2007 Report Share Posted June 26, 2007 The factory harness isn't using any relays for the AC, Their is a table in HPtuners that adjust air flow at idle, it is in the dynamatic aiflow. I was told to set the fan 1 to .10 gsec and fan 2 to .20 gsec. This compensates for load on engine (alt). For some reason GM did not have the fans come on with the AC request. Sombody can correct me if I'm wrong. How do I get a hold of Nelson to get a harness? Or has anyone verified how to control the fans programming the factory pcm and uding the GM harness? Link to comment Share on other sites More sharing options...
ccgoodwrench Posted June 30, 2007 Report Share Posted June 30, 2007 How do I get a hold of Nelson to get a harness? Or has anyone verified how to control the fans programming the factory pcm and uding the GM harness? I would just get the gm harness it was like $125, you also need to connect it to pin 33 and 42 of the pcm, you will need tunning software to program the fans (HP tuners). In a early post you I said to increase dynamatic airflow i meant to say idle air flow. Link to comment Share on other sites More sharing options...
4ws f 7 Posted July 7, 2007 Report Share Posted July 7, 2007 I would just get the gm harness it was like $125, you also need to connect it to pin 33 and 42 of the pcm, you will need tunning software to program the fans (HP tuners). In a early post you I said to increase dynamatic airflow i meant to say idle air flow. Am I correct to say that pin 42 is for engine coolant temp. signal to turn fans on? And pin 33 is? Link to comment Share on other sites More sharing options...
ccgoodwrench Posted July 8, 2007 Report Share Posted July 8, 2007 Am I correct to say that pin 42 is for engine coolant temp. signal to turn fans on? And pin 33 is? pin 42+33 is the ground trigger for the relays, one is for low speed and one for high speed can't remember which pin is low or high Link to comment Share on other sites More sharing options...
SS_bnoon_SS Posted July 9, 2007 Report Share Posted July 9, 2007 pin 42+33 is the ground trigger for the relays, one is for low speed and one for high speed can't remember which pin is low or high 42 low 33 high Link to comment Share on other sites More sharing options...
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