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Hi/ low fan switch


jaredbonner1
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Has anyone tried to make their own fan control switch? I made one on my Saturn by tapping into the relay and connecting it to ground on a switch, but the grand prix has 3 different fan relays and I could only get one fan to work at a time.

 

ZZP has one for sale but I really don't think it's worth what they are asking...

 

Screenshot_20170321-094128_zps2c3outav.p

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I'm guessing you have a 97-03 Grand Prix.

 

The computer already does everything you want to do, just set the turn on temps and enjoy

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Theoretically it should just be a basic switch. Maybe try a thicker gauge wire and separate that wire into each of the 3 relays. I'm assuming that switch is commanding it via OBD but I'm probably wrong on that one. It looks like only one wire that ZZP has on that switch. Maybe see if you can find the directions for how to install that and see where it connects

 

 

Sent from my iPhone using Tapatalk

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Well I live down in Mississippi and my car gets too hot with the supercharger for my liking. I already put a 180 t-stat but if I'm sitting in traffic it can get up to 215 and 220. I could get it with my tuned PCM but I have a lot of stuff to spend money on before I can get around to a PCM.

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I'm guessing you have a 97-03 Grand Prix.

 

The computer already does everything you want to do, just set the turn on temps and enjoy

It is an 01. All I have is an old adapter and torque pro. What do I need to start setting things like that? Do you need a hp tuner and a computer or is it easier than that?
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Buy your own interface and you'll have the ability to set fan temps and much more.. I have my primary temp at 190 to coordinate with a 180 stat and secondary at 205 to coordinate with a 195 stat. A switch under the hood select which input to the PCM is being used to throw both relays at once. I call it my summer / winter switch and change the thermostat twice a year. Summer I run about 187 with a stock radiator. I don't have A/C or it would get complicated as the secondary fan control is also run via A/C pressure to cool the condenser.

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I do agree that the cleanest way is to do it via tune.

Has anyone tried to make their own fan control switch?

To answer your question directly, though, I have done this before many times. Your fans have three relays because they run in series on low and parallel on high. Ground relay 1 for low speed and all three for high speed. Although this schematic is not specific to your vehicle, most of that era gm fans that have low and high speeds work in the same way. Again, the wire colors and such are not grand prix specific.

 

2008-03-31_221607_Cooling_fans_06_1500_5

 

One last note: I would use something to isolate the ecu from your grounds (use either multipole switch or additional relays). Although you may not hurt your ecu by grounding what is ungrounded in this specific case, it may set a code.

Edited by vipmiller803
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I'll have to do this on my Z34 if my fans work because they don't come on... Not even when I jump the ALDL to pull codes (fan usually would come on).

 

Anyways, wiring is cheap at Walmart and I'm pretty sure they sell switches there. You could probably do what zzp sells for $20

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