moregrip Posted October 6, 2011 Report Share Posted October 6, 2011 (edited) so I'd like to build or buy and efan harness that uses both pin 33 and 42 to activate, but has some kind of feature that doesn't shock the electrical system (maybe 6v initial then 12v.........is there a better way) Also want ice cold A/C all the time. Want a manual switch over-ride to turn them on. How do I do this? Or who sells it? I would rather make my own as its cheaper but not at the expense of 7days research to understand it all! Can I modify my existing single pin activated harness? (Nelson's) Edited October 6, 2011 by moregrip (see edit history) Quote Link to comment Share on other sites More sharing options...
chpspecial Posted October 6, 2011 Report Share Posted October 6, 2011 Yes you can covert your nelson harness to a dual pin... you can do this by changing the A/C relay from a 12v+ trigger to a neggative trigger. So just remove the negative from said relay and connect that to you pcm's second trigger, and the 12v+ going to your A/C gets connected to a 12v constant when key on... that should give you OEM style control of the fans. Don't forget to get your PCM tuned for SERIES PARALLEL FANS. For your other question, we don't have soft start capabilities with our PCM. The best we have is that when FAN 1 is comanded on by the PCM, the fans run in series resulting in half fans speed and each fan sees 6 volts of power. When both fan 1 and 2 are commanded on, they switch from in series to parallel, and then both get 12v or full power and speed. Quote Link to comment Share on other sites More sharing options...
moregrip Posted October 8, 2011 Author Report Share Posted October 8, 2011 Yes you can covert your nelson harness to a dual pin... you can do this by changing the A/C relay from a 12v+ trigger to a neggative trigger. So just remove the negative from said relay and connect that to you pcm's second trigger, and the 12v+ going to your A/C gets connected to a 12v constant when key on... that should give you OEM style control of the fans. Don't forget to get your PCM tuned for SERIES PARALLEL FANS. For your other question, we don't have soft start capabilities with our PCM. The best we have is that when FAN 1 is comanded on by the PCM, the fans run in series resulting in half fans speed and each fan sees 6 volts of power. When both fan 1 and 2 are commanded on, they switch from in series to parallel, and then both get 12v or full power and speed. Great info! Would you happen to know how I go about wiring a manual on/off switch in the above setup?? Quote Link to comment Share on other sites More sharing options...
chpspecial Posted October 8, 2011 Report Share Posted October 8, 2011 Sorry I forgot about that part. Just run a switchs to both trigger pins and make sure you GROUND them. Do not apply any 12v source to them otherwise you will fry the efan driver in the pcm. sent from my thunderbolt Quote Link to comment Share on other sites More sharing options...
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