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Problem with Nelson fan harness please help

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Old 02-09-2006, 09:14 PM
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Default Problem with Nelson fan harness please help

My fans (05 truck fans) on my 02 chevy are not coming on automaticly. The only time they come on is when I touch the extended ground wire (for a manual switch) to a ground. The motor gets up to 210 and the fans are not coming on. I have a 160 termostat. I followed the directions that were sent with the fans. Any idea what is going on?
Old 02-09-2006, 09:41 PM
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Default Connect that gnd

Let the truck cool and connect the gnd. Then crank it to see if it comes on. That gnd might be for the manual switch and the auto switch. Seems like theyd have one gnd for both. Try that and see what happens. Just make sure the truck is cooled down completely then crank it and see what happens.
Good luck.

Derek
Old 02-09-2006, 09:47 PM
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stupid question, but......is your PCM enabled to control the fans? Pin 42 "turned on"?

Another stupid question, but....did they set the correct turn on values up in the PCM? Are the turn on values compatible with the 160 degree thermostat? They may be set to kick on for a 195 stat.
Old 02-09-2006, 10:34 PM
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Make sure you seated pin 42 all the way as that is ground also.
Old 02-10-2006, 12:06 AM
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Originally Posted by stall speed
Make sure you seated pin 42 all the way as that is ground also.
winner! if you have everything enabled in the PCM take off the clear blue plastic cover covering all of the pins and push pin 42 in until its seated ALL THE WAY IN.youll probably feel a little snap once it gets into place. you can see how its suposed to be after you pull off the blue cover. using a safety pin made it easier for me.
Old 02-10-2006, 06:23 AM
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I will see but Allen said everything was turned on in the PCM for the fans. I will take a look this weekend and see.
Old 02-10-2006, 09:11 AM
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Originally Posted by TXsilverado
winner! if you have everything enabled in the PCM take off the clear blue plastic cover covering all of the pins and push pin 42 in until its seated ALL THE WAY IN.youll probably feel a little snap once it gets into place. you can see how its suposed to be after you pull off the blue cover. using a safety pin made it easier for me.

This was my problem initially too, I spent hours messing with the tune and checking for breaks in the wires, finally pulled the connector off the PCM and looked, and the pin was only seated about half-way. Double-check yours.
Old 02-10-2006, 11:38 AM
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Originally Posted by Dark Halo
I will see but Allen said everything was turned on in the PCM for the fans. I will take a look this weekend and see.
Probably a pin not seated well then....as already stated.

Good luck.
Old 02-10-2006, 02:19 PM
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not to jack your thread dark halo but i have the same problem with mine except with ls1 fans.

when i talked to allen about my retune i made sure he tuned the pcm for them. i've been having it ran to a manual toggle switch since may.

from the toggle switch (source prong), ran a wire from there and taped into the blue wire. from the toggle switch (ground prong), ran a wire from there to a good ground.
when the switch is on both fans are on low. when the a/c compressor kicks on, both fans turn on high

i've let the temp get high and they have never turned on.

am i doing something wrong. thanks... lance
Old 02-10-2006, 06:41 PM
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mine have yet to come on when temps hit 210 also.. they work fine with the A/C and deforst though...

i gave up cause I checked everything 40000 times and cant get them to come on low when it hits 210. Im just gonna ru na ground wire so i can toggle them on low speed at drivethrus and etc


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