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Aug 13, 2005 | 07:56 PM

VT Solo2

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From: Ashburn VA

Coolant Fans

Hi everyone, I'm wanting to wire up a switch to manually control the fans in my '96. Has anyone done this? I was thinking about just wiring a switch to ground the dark blue wire in the secondary fan relay. As far as I can tell, this should turn on the secondary fan. I also saw in the schematic in the shop manual that it will also activate the third relay, which has some control over the primary fan also. I haven't been able to figure out why GM used 3 relays to control 2 fans. Can anyone explain how this all works together and when the fans come on? So very confused right now.

Thank you...

Aug 15, 2005 | 05:49 PM

VT Solo2

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From: Ashburn VA

No one?

Aug 15, 2005 | 07:35 PM

Slalom4me

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From: Edmonton AB

There are a couple of entries in the C4 Tech Tips section.

The topic has come up fairly often, so a search of the archives
should bring up quite a lot of info.

.

Aug 15, 2005 | 08:45 PM

the blur

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From: cyberspace NY

don't mess with it. they were very cleaver in 96. both fans either run in low speed or high speed. very cleaver design. they series the fans to split the voltage, 6v on each fan = low speed.
12 v on each fan = high speed. therefore 3 relays.

I was very impressed when I saw the design.

Aug 15, 2005 | 09:49 PM

VT Solo2

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From: Ashburn VA

Quote:

Originally Posted by the blur

Yeah, that's the conclusion my roommate and I came up when we tried to figure out the schematic and what GM was trying to do. Oh well. Well, thank you for your help, I do appreciate it!

Aug 15, 2005 | 10:20 PM

Atok

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From: NS

You would be better off to get the PCM reprogrammed to turn the fans on when you want them on.

Aug 15, 2005 | 10:21 PM

VT Solo2

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From: Ashburn VA

Quote:

Originally Posted by Atok

You would be better off to get the PCM reprogrammed to turn the fans on when you want them on.

I think you can do that with a Hypertech too, right? I was just trying to do an inexpensive mod, so I think it can wait...

Aug 16, 2005 | 07:56 AM

Atok

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From: NS

Yeah, and I think TunerCat will soon support the '96 PCM, if they don't already. TunerCat would be cheaper than a HyperTech and you will be able to change whatever you want. Ask about it in the Scan & Tune forum.