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Electric fan interference

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Old Apr 11, 2009 | 10:26 PM
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Default Electric fan interference

Anyone else have an interference problem with their electric fan?

I'm running a tauras dual speed fan, when it turns on the engine starts running like crap. I ran a scan log and the sensors are all over the place once the fan turns on.

I have it wired with a relay and the relay power source is the alternator. Is there some kind of filter I need to run?
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Old Apr 11, 2009 | 10:34 PM
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move the source directly to the battery..
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Old Apr 11, 2009 | 11:15 PM
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Thanks man, will try that
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Old Apr 17, 2009 | 08:06 PM
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Well, tried running the relay feed to the battery and it has the same problem. Any other ideas?
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Old Apr 17, 2009 | 09:01 PM
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could be bad grounding ?.. check to make sure the grounds are good or that you even have one.
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Old Apr 17, 2009 | 09:09 PM
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Ground is good. I wonder if the stock alternator has enough juice to run this fan.
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Old Apr 17, 2009 | 10:14 PM
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Definately sounds like a power issue..does it say anything like it may need more than one Relay?
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Old Apr 18, 2009 | 07:23 AM
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I have a Taurus fan on my truck, it does the same thing. Those fans are power hogs on start-up. The fan kicks on and the engine stumbles a second then all is well.
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Old Apr 18, 2009 | 09:12 AM
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I could see something like this happening if you are somehow feeding back the fan draw to the alternator voltage sensing wire.

Where does the voltage sensing wire from your alternator hook into? Should be somewhere in the harness. An under dash guage works well.

Like someone said hook the fan power wire as close as you can to the battery. The battery is about the best filter capacitor you will get. Clean your battery posts to make sure there is a super clean connection.

Double check your engine grounds. If the PCM and various engine components are not all hooked together it could be inducing voltages onto the PCM.

On fan start up the battery should provide the surge amps needed to get things going. When running steady state the alternator should provide the juice. Check your volts when the fan is off and when it has been running awhile. If the volts don't drop below say 13 volts then the alternator is up to it.

If you do all the above and you stil have problems, hit a pick and pull and get another fan. Maybe the brushes are shot on the one you have. Most pick and pulls will let you exchange things like fans.
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