Fan wiring
Thread Starter
On The Tree
Joined: Feb 2002
Posts: 188
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From: Chicagoland
Re: Fan wiring You can have the 2 outputs signal low speed and high speed operation as well, but this requires some tricky wiring, and 3 relays I believe.
Get the factory Fbody wiring schematics to do this.
Get the factory Fbody wiring schematics to do this.
Staging Lane
Joined: Jan 2003
Posts: 57
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From: NJ
Fan wiring Can someone shed inf. on wiring of the fan. I have mod. harness and there is two wires. Do I have to use a duel fan. Or I can use a single fan with 2 speed. But how do you wire them to work like 1st and 2nd speed. Any info appriciated. Thanks
Joined: Nov 2001
Posts: 1,707
Likes: 33
From: Anderson, Indiana
Re: Fan wiring The fans can be configured in different ways. You can run one fan only, two fans at two different temps, or two fans on at the same temp.
To wire up fans and have them controlled by the PCM, the relay is wired so that the "high" side of the relay coil (+) is powered from any "key on" source. This is a pink wire on GM harnesses. The PCM then completes the "low side" to ground of the coil when the programmed temperature is reached. In other words, the PCM grounds the relay to energize it. On GM harnesses this is dark green for the primary fan and dark blue for the secondary fan.
Then, on the contact side of the relay you have a heavy gauge wire coming from the battery to one side of the relay, and the other side of the relay goes to the fan (+).
Then when the correct temperature is reached, the PCM grounds the relay coil, the coil energizes, the contacts close, and battery voltage powers the fan.
To wire up fans and have them controlled by the PCM, the relay is wired so that the "high" side of the relay coil (+) is powered from any "key on" source. This is a pink wire on GM harnesses. The PCM then completes the "low side" to ground of the coil when the programmed temperature is reached. In other words, the PCM grounds the relay to energize it. On GM harnesses this is dark green for the primary fan and dark blue for the secondary fan.
Then, on the contact side of the relay you have a heavy gauge wire coming from the battery to one side of the relay, and the other side of the relay goes to the fan (+).
Then when the correct temperature is reached, the PCM grounds the relay coil, the coil energizes, the contacts close, and battery voltage powers the fan.
__________________
91 Z28 LS2 408CI, LS9 Supercharger, LPE GT7 cam, Yank3000, 3450 raceweight.
Latest numbers: 9.71 ET, 141.42 MPH, 1.40 60' , 610 RWHP Mustang Dyno
www.speartech.com
91 Z28 LS2 408CI, LS9 Supercharger, LPE GT7 cam, Yank3000, 3450 raceweight.
Latest numbers: 9.71 ET, 141.42 MPH, 1.40 60' , 610 RWHP Mustang Dyno
www.speartech.com
