EFan problem....not a tuning issue
03-06-2011, 11:46 AM
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EFan problem....not a tuning issue
Anyone able to tell me what would cause the EFans to start up immediately during the ignition on? As soon as i turn my truck on pin 42 turns the ground connection on and starts the fans. I checked the tun and had a couple other eyes on it and the tun file is setup the right way, so im looking in to mechanical reasoning now. A/C pressure switch? Any other Efan relays/fuses under the hood? Faulty wiring to the PCM...etc!?!?
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Thanks
03-06-2011, 02:09 PM
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Yeah i had it for a while, and the issue started sometime ago. I just never delt with it till now. I HAD the neslon harness, until one day i noticed my fans not running. When I pulled the harness out the relays were basically melted so im not sure exactly what happen. I bought the harness way back when he first started building them...
03-08-2011, 07:48 PM
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Ok so here's what i DO know... it doesnt matter which PCM i place in it, it does the same thing for all the PCM's. So i rule that out as a factor. I know its not the wiring harness for the fan because i volt metered the wire on 42 and its constantly grounded when ignition on. What else am i missing here!?!? A/C pressure switch???
-Is there a switch other than inside the PCM that tells it at what temps to turn the fans on or maybe another Relay/Fuse under the hood?? Or is that simply controlled by the PCM and the reading it gets from the ECT!?
-Is there a way i can check the A/C pressure switch or is it pretty much just replace and see the results?
-Is there a switch other than inside the PCM that tells it at what temps to turn the fans on or maybe another Relay/Fuse under the hood?? Or is that simply controlled by the PCM and the reading it gets from the ECT!?
-Is there a way i can check the A/C pressure switch or is it pretty much just replace and see the results?
03-08-2011, 10:10 PM
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You should be able to unplug the ac pressure switch and eliminate it as the culprit. I think it is a normally open switch, which would mean if the AC is off, it should not close the circuit.
You could also have a stuck relay. If you have the 3 relay setup you can try swapping them around and see if anything changes.
You could also have a stuck relay. If you have the 3 relay setup you can try swapping them around and see if anything changes.
03-09-2011, 05:16 AM
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You should be able to unplug the ac pressure switch and eliminate it as the culprit. I think it is a normally open switch, which would mean if the AC is off, it should not close the circuit.
You could also have a stuck relay. If you have the 3 relay setup you can try swapping them around and see if anything changes.
You could also have a stuck relay. If you have the 3 relay setup you can try swapping them around and see if anything changes.
As for the harness, im positive it isnt the issue because, when i remove the harness completely and volt meter test the 42pin wire, it is constantly grounded when the ignition is on whether im at "Fan on" temps or not!!
Oh, where is the A/C pressure switch actually located?
03-11-2011, 06:05 PM
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Damn I disconnected the switch on the passenger side up top...its still got the fans running! Is there another switch im missing maybe a high and low!? I only pulled the one that is on the line up top side on the passenger side. Can someone do a quick check and see if by disconnecting that upper switch if the fans will come on prematurely. It almost seems to me that the fans would still kick on even if its disconnected kinda like a fail safe to a non working switch.
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03-12-2011, 02:44 PM
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The switch you need it the one on the compressor. That's the high side switch. The pressure gets high, it closes to signal the PCM to turn the fans on to cool the refrigerant to bring pressures down. What harness are you running now? Does it strictly run off of the PCM or is it tapped into the A/C compressor?
03-12-2011, 05:06 PM
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The harness is completely removed now because im going to make a new one... but it WAS strictly off the PCM after the the first one i had which was from nelson which utilizes both pcm and a/c. Story line is as follows, Neslon harness went in and somehow shorted out after a year or so of usage. When that happen the fans were always on. I thought i jacked my pcm so i replaced it with a new, and still the fans stay on. So I made a new harness that takes the a/c out of the equation and only uses pin 42 to signal the relays on. The fans were individually grounded so the relays supplied a separate 12v signal to each fan causing them to run in "High" mode when they are on. The harness i made for this was a simple 2 relay harness, none the less, the fans were still always on when the ignition was on ever since the nelson harness blew up. Now I pull my harness out to test and see if there was a problem with the relays that i reused from the nelson harness... turns out the PCM is always firing out a ground signal to 42 when the ignition is on.
So now here I am trying to figure out what is causing it to always be on. I will go try and remove the one on the compressor itself and see if that turns it off. I removed the one top side on the passenger side of the truck already thinking that was the switch i needed to remove but it didnt change the fan status.
So now here I am trying to figure out what is causing it to always be on. I will go try and remove the one on the compressor itself and see if that turns it off. I removed the one top side on the passenger side of the truck already thinking that was the switch i needed to remove but it didnt change the fan status.