GRAND PRIX 85 Grand Prix with 86/87 GN fan harness

copperhead

Apprentice
Aug 25, 2016
99
18
nixa, MO
Hey guys, been a while but I'm back with a new ride! I purchased an 85 Grand Prix and currently swapped to a cold case radiator with dual fans(part# vdo fa70020). The fans came with a caspers electronics wiring harness(part# 109069) for a GN/turbo regal. I'm fairly wiring illiterate so to speak, but is there a way to make this harness work?

Car has a 10.8 1 383 built for boost. 2004r and 8.5 out of an 85 GN. Wilwoods all the way around with a manual conversion and level 2 road race suspension from qa1. Will be swapping to a tkx 5 speed soon and building the car for Pikes Peak Hill Climb.
 

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pontiac guy

G-Body Guru
Oct 28, 2016
551
93
Royse City, TX
85 and 86 actuate so switch one side and ground the other. 30 is power to the relay. 87 is power to the fan. Note 87a will have power when 87 doesn't. Basically when the relay isn't triggered. That's a shitty relay for that job. Think of it like either or. You can use it to kill power by switching or provide power.
 
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copperhead

Apprentice
Thread starter
Aug 25, 2016
99
18
nixa, MO
85 and 86 actuate so switch one side and ground the other. 30 is power to the relay. 87 is power to the fan. Note 87a will have power when 87 doesn't. Basically when the relay isn't triggered. That's a shitty relay for that job. Think of it like either or. You can use it to kill power by switching or provide power.
So if I'm getting this right.

Pic 1 hot wire to breaker
Pic 2 breaker to fan relays.
Pic 3 fan relays to 3rd relay

I picked up this 3rd relay also. So on 3rd relay I would ground 85 or 86, put 12 volt ignition to 30 and power 87?

And this will give me low speed fan with ignition on?
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copperhead

Apprentice
Thread starter
Aug 25, 2016
99
18
nixa, MO
81cutlass is an engineer, perhaps he could answer some of your questions?
I appreciate it! I wired in the 3rd relay tonight. 30 and 87 have power. 86 is ground and haven't figured out 85. I'm assuming Im supposed to wire a thermostat switch from the manifold and when it grounds, the second speed kicks on.

I hate wiring. Lol
 

fleming442

Captain Tenneal
Supporting Member
Dec 26, 2013
13,085
113
Just remember: 85 & 86 have to be opposite polarity. So if you grounded 86, 85 needs to be 12v+. The problem you have now is that most temp sensors are ground. If you want to run a thermostatic switch, you need ign, then provide the ground through the sensor/switch.
 
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81cutlass

Comic Book Super Hero
Feb 16, 2009
3,519
113
Western MN
81cutlass is an engineer, perhaps he could answer some of your questions?

Hey, I am not a spark-E, I am a mech-E!!!

But yeah I shot him some comments through a PM.

I don't see any way to trigger the relay here. That's the biggest thing. Need a PCM or thermo based switch to trigger the relay.
 
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