This simple modification gives you almost complete control of the electric fan in front of the AC condenser.
I say almost because the fan will always be on when the key is on or when the engine is running. A toggle switch provides manual control of low and high fan speed.
This will probably be most beneficial to folks who have removed their engine driven fan and live in warm climates. But it's easily reversible so that come winter the fan relay can be put back in its original position.



The white wire leading away from the fuse box leads to a SPST toggle switch on the dash. The other connection from toggle switch goes to ground.
The switch positions are:
Up= HIGH
Down= LOW

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U.S. Army Retired

I will have to use this trick when I install an E-fan soon. Thanks for sharing.

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Phil
2005 131k 3.7 Gasser (Lifted-CRD Springs, 4.10 Gears, F+R DTT, Teraflex 2wd Low, Skidrow/Mopar Skids, Rock Lizard Super Skinks, Goodyear Wrangler Authority 31x10.5-15)
2012 Triumph Tiger (TKC 80 Front Tire Heidnau K60 Rear, Crash Bars, Skid Plate, Bark Busters, Pelican Case Top Box)

It was a hot weekend here in JAX, 95F for most of Sat and Sunday. Looks like that will continue thru this week. The fan switch worked good.
When driving around town with the AC on you definitely want to keep the fan on HIGH.
Also, when its this hot, the ECU likes to run the fan for about a minute after shutting the engine off and removing the key. Keeping the fan switched to HIGH will allow this to happen.
When switched to LOW, the fan will just turn off when the ignition switch is turned off.

If you wanted FULL manual control of the electric fan you could replicate the same wiring on the other fan relay and use a DPDT center-off switch that is ON-OFF-ON.
Not a momentary switch that is (ON)-OFF-(ON).
The single wire from each relay would go to the center posts of the toggle switch.
One of the top posts would be connected to ground and both bottom posts would be connected to ground.
The switch positions would be:
Up= HIGH
Middle= OFF
Down= LOW
However, this would override any electric fan control from the ECU. When you turn off the ignition the fan will completely turn off regardless of temperature and switch position.

Also, either of these fan relay/switch modifications will throw a code for a bad fan relay because the ECU can no longer sense the presence of the relay.

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U.S. Army Retired