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Derale fan trigger wire quick question

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Old Aug 29, 2015 | 07:06 PM
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Default Derale fan trigger wire quick question

I recently wired two derale 16925 pusher fans into my car and tried them out today for the first time. I just followed the instructions that came with the fans and used the supplied relays. I tapped the wire from (red connector pin 33, which is high speed cooling fan relay control) as my trigger wire to the relays. As the car heated up, the fans would not come on. I am assuming the trigger wire I tapped into is sending a ground signal and not a 12v signal to the relays?

I just wanted to make sure the fans would work so I cut the trigger wire and simply touched it to the positive side of the battery. The fans kicked on and ran just fine. Am I tapping into the wrong wire for the high speed signal? Any help is appreciated.
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Old Aug 30, 2015 | 09:08 PM
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I just tapped the factory trigger wire in the fan harness and wired the rest per instructions.
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Old Aug 30, 2015 | 11:25 PM
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Originally Posted by Fier23
I just tapped the factory trigger wire in the fan harness and wired the rest per instructions.
Thanks for the reply. Alot of my factory wiring is out of the car so I am just tapping for signal off the pcm.

I now know that the pcm sends ground signals and not postive voltage to the factory fan relays. Pin 42 (blue connector) is the low speed fan signal and Pin 33 (red connector) is the high speed fan signal. Does anyone know if the low speed signal stops once the high speed signal is activated? Or does the pcm continue to activate the low speed signal once high speed fans are needed?
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Old Sep 1, 2015 | 11:17 AM
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Bump. Somebody has to be able to help this guy out?? Sorry I don't have that answer.
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Old Sep 1, 2015 | 02:17 PM
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I did the same at this guy ^. Sorry, no answer here for you
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Old Sep 2, 2015 | 12:03 AM
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Thanks guys. I found out that once the low speed fan signal is activated, it continues to be sent even when the pcm commands the high speed fans. I just used the pcm (low speed) ground signal as my coil trigger and they work great now.

I was worried about using the low speed signal as the trigger because I wasn't sure if that signal is deactivated when the high speed signal was activated. Meaning my fans would turn off.

And the reason I'm not using the high speed signal right now to trigger my relay was because I tried it and couldn't get the fans to come on even once the car got up to the 220-230 range. I don't have a way to read the pcm, but I believe the temp setting for high speed fans is set too high at the moment.
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