Ground Signal From OEM Fog Switch

I was thinking of using the OEM fog light switch to control the fan in my 98 Cherokee, but I would need the signal wire to be ground rather than hot. Has anyone rewired the pigtail so it provides a ground signal rather than a hot? I think it would be similar wiring to the OEM extended idle wiring when using a fog light pig tail but I am not sure if the internal contacts are the same between a fog light switch and the extended idle switch:

Extended Idle Wiring Using Fog Light Pig Tail
Orange #1 - Ground
Blue #2 - Ground Signal Wire
Purple #3 - 12V Switched Power
Black #4 - Dimmer

Fog Light Switch Wiring Using Fog Light Pig Tail
Orange #1 - Dimmer
Blue #2 - 12V Switched Power
Purple #3 - 12V Signal wire
Black #4 - Ground

Let me know if any of you have come up with this before. I know I can use a standard switch but I would like to keep the switches factory in the bezel.

The cooling fan or the climate control fan ?

Either way, use the switch to control a relay and the relay to power the fan.

Electric cooling fan, forgot to mention that. I will be using a relay but I was going to do whats called a switched ground activation.

Use the stock wiring to control a switching (NC/NO) relay? Connect the wire to be grounded to 87 (I believe that's the NO terminal, double check), and a grounded wire on 30. Relay on, wire grounded. Relay off, wire open.

And out of curiosity, are you adding a fan, or going to put the aux fan on a switch?

A five terminal relay will have an 87 and 87a terminal. 87 switches the circuit ON and 87a switches the circuit OFF when power is applied to the relay.

I'm not sure if you're trying to set this up like the write-up I did on wiring a switch to activate the fan using the factory wiring or not, but I think the same principles would apply here. Thinking about this also got me thinking about the question you asked me the other day about using a fog light switch to activate extended idle....

I think the answer to both questions is going to be no, it won't work, and here's why...

On the fog light, the 12V+ signal sent out on Pin#3 comes from Pin#2.
This 12V+ source on Pin#2 is also used to power the switch activation light.
If you turn Pin#2 into a ground so that a ground signal is sent out instead, the activation light will be grounded on Pin#2 and Pin#4 and the bulb and will not turn on.
If you try to fix this problem by turning Pin#4 into a 12V+, then the panel light (Dimmer) will get 12V+ from Pin#4 and ~12V+ from Pin#1 and the bulb will not turn on.

So... I think you could use a factory Extended Idle switch to operate the extended idle function or to control your electric fan via a switched ground activation. But, I don't think you can use a fog light switch for either project. The only way to know for sure would be to try it, but it looks like you're going to have to break down and buy an extended idle switch if you want to do this with OEM switches.

You options are limited with the OEM switches since both lighting circuits in the switch share a common ground. The Carling switches give you more flexibilty because they have an individual ground pin for each light circuit.

Has anyone see a Carling's switch with the High Idle symbol and wording ? I have two of their switches installed already in the bottom of the console by the Tranfercase Shifter. I use one for my air compressor and the other is an extra but is wired up to the headlight dimmer switch already. I'd just have to change the cover if can find a matching one just with an amber lens. Looking to use it for an extended idle set up.