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is it possible to check the ground signal that triggers the fans?

 
Old 09-01-2014, 07:15 PM
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Default is it possible to check the ground signal that triggers the fans?

long story short i have wiring/cooling issues. Both fans are turning on at the same time or the one signal is turning on both or vise versa....really i have no clue whats going on. Is there a way to test the 2 wires coming out of the pcm to see when they are giving off a signal to turn the fans on/off? Being ground switched, i dont know how to check that. Or could my pcm be screwed up and grounding out making the fans not work right?
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Old 09-01-2014, 07:35 PM
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are they PWM?
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Old 09-01-2014, 07:41 PM
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PWM? Don't know what that means. There Derale fans, I had them wired but the fuses got too hot and started to melt. Rewired them today with new fuses holders and ran thicker wire but they are not working like there supposed to and blowing fuses. Being ground switched, am I supposed to wire them differently?
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Old 09-01-2014, 07:56 PM
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What do you mean you had them wired but the fuses got too hot? Are you not using the factory wiring with the 3 relays controlling the 2 fans?
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Old 09-01-2014, 08:02 PM
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No, rewired car from scratch. "Race car wiring" if you want to call it that. I have them triggered from my PSI harness and it's all wired as a standalone unit.
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Old 09-01-2014, 08:56 PM
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Without seeing a schematic of what you are trying to do it will be impossible to help. I hope you are still using relays of some kind. Stock wiring uses 2 outputs with 3 relays to either configure both fans in either series or parallel. The PCM cannot drive fans directly with its ground outputs. It can only drive relay windings.
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Old 09-01-2014, 09:02 PM
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yea im using relays, lol. Im more curious to see if theres a way i can test the 2 wires in the harness to make sure there giving off the right signal at the given programmed temps (180/200 im assuming)
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Old 09-01-2014, 09:12 PM
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Check it with a volt meter just like you would check any electrical circuit. If the PCM is not outputting a ground you should see 12V on the terminal sourced by the 12V on the other side of the relay winding.
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Old 09-01-2014, 10:34 PM
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You can turn them off and on with a scan tool to test the wiring, if that works and your temp gauge works then they should come on at the right temp.
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Old 09-04-2014, 01:20 PM
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Ground your relays with a direct ground to see if they work properly without the pcm. Then you will know if its the pcm or your wiring.
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Old 09-05-2014, 07:33 AM
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So back to this crap. I rewired both my fans last night on completely 2 separate circuits. Each fan has its own power, ground, relay, fuse etc., however when the low temp signal kicks on for the first fan, both of the fans turn on, on top of that the high temp fan kicks on a second before the low temp fan turns on. How the hell is that possible? It was all working fine the few hundred miles iv been driving it, then I blew a fuse due to too small of wire (14g) feeding the fans that led to the rewire with 12g. After the rewire the fans have been wrong.
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