will someone explain what the harness does? i heard you still have to reprogram the computer to turn on the fans? if so then whats the point in the harness? can someone explain? thanks

 

Not exactly sure what all the Nelson harness offers, but the one I have has to have the PCM programed to turn on the fans if you want to use that feature. It also has a programamble thremostat and an A/C turn on lead. Those don't have to use the PCM to work. You can have them turn on with the A/C lead (which Nelson has), the thermostat, or PCM controlled (which Nelson has). You will have to use a laptop based tunner to access the PCM feature of one of these harness'. If you use the PCM, you don't need to use the thermostat.

 

With the nelson harness you will have to have the computer re-programmed to activate the fans at temp.

 

The harness provides the wiring for control and powering the fans. Control comes from the PCM. Basically plug the harness to fans. Connect Ground and 12V battery, one wire to PCM, one wire to AC Compressor. Complete with relays, fuseable links, and connectors. You must turn on the PCM control which monitors coolant temperatures to turn the fans on and off.

 

I can activate the computer control before installing the fans correct?




Im saying this because i have access to LS1edit right now, which is what i tuned my truck with, but i have not installed the fans right now. It wouldnt hurt anything to have the computer turn on the fans now, would it? When i install my fans, i want them to work right away, and i will probably not have access to LS1edit.

 

Yes you can. Will not be a problem.

 

Thats what i figured.

 

Here is a recent email I recieved from Allen Nelson regarding the fan harness.

The fan harness we supply comes with everything you need to get your fans working correctly. I supply the OEM connectors for the ls1 fans and additional hardware for the flex a lite fans. The harness is completely wrapped in loom, all joints are soldered and I use fusible link instead of fuses, just like your starter wire.

To install, you simply supply ground and power, tap into the a/c green wire and push the supplied wire and terminal into the pcm. All ground, power and a/c points are at the red junction box on the side of the driver’s side engine. So there’s no hunting for wires. The pcm wire simply pushes into the blue connector at pin 42.

The harness has three speeds. Here’s how it works.



The pcm is programmed to ground pin 42 when it reaches a turn on value and off when it reaches a turn off value. When it does ground the pin, it will activate both fans and turn them on low speed.

When the a/c is turned on, the green wire has 12volts applied; both fans will turn on high, as long as the pcm has reached its turn on value.

If the engine hasn’t reached its turn on value and the a/c is turned on, one fan will turn on high. This will keep the a/c cool.



The harness is $89 and I can ship immediately.

 

sounds good except for one fan turning on high and one on low and all that crap...im not sure if im gonna get one...how does everyone else like theirs?

 

Mine works great. Plug and play.