Turbocube

I wanted to do the mod to be able to manually switch the auxiliary fan on and off, but they all seem finnicky. My XJ has a wire that simply gets power (I believe its directly from the battery/alternator) that used to power fog lights.

I was wondering whether or not it were possible to simply use this wire to send power to the electric fan whenever I want, because there's already a switch in the cabin that turns it on and off.

However, the problem is that I'm not sure what voltage/amperage the electric fan motor needs, so I'm reluctant to just wing it.

Anybody know? Its a discontinued Mopar # 52005748

CCKen

Why do you want to do this?

The fan uses a 40 amp relay to power it.

There are several threads in the Jeep XJ forums that describe a manual on-off switch mod for the fan. Goole search them.

Turbocube

I'm aware of the other mods. I just think they over-complicate things. Why not just run a little wire down into the relay to trigger it, or in my case just power the fan directly via manual, since I've already got the means?

Not saying there's anything wrong with the mods. Just trying to adapt it to my own situation.

So the fan gets 40 amps power, then?

DFlintstone

It's never a bad idea to listen to Ken. "why do you want to do this?" It should work the way it is designed. With a 195* t-stat, and the e-fan coming on at 218* you should be good to go...

Turbocube

I'm not the only one who does this mod. Sure, it will turn on automatically at 218 F but why not be able to control it yourself if you want?

You are promoting upgraded injectors in your signature. I'm sure you understand.

dwright98xj

Hi Turbo,

I believe the point the gentlemen here are trying to convey is that it is not a "mod" but a workaround alteration from the original intended design.

That said....

I used to work on 3rd gen f-bodies (Camaros and Firebirds) and the electric fan control on them were habitual problem children and it didn't very long for the engine to overheat seeing there is literally no grill opening on those cars.

So, having been through this before, my XJ fan was not operating correctly combined with other system issues that needed addressed, but it was a daily driver that my now ex-wife needed to use daily, badly. Not having much time to diagnose, I did by pass as such:

Run a positive feed wire from a hot source (I just tapped directly to the battery cable). Put a 30A inline fuse at the start of your hot feed! run the hot feed to the hot side wire of the fan. From there, you run the ground side into the cab to your desired switched input, then to ground (for safety I ran it back out to a fender bolt). Boom done. Pretty basic.

Now that the XJ is in my possession, I do plan to return to normal.

Negative side effect:

My ex wasn't the brightest (hence ex ) and would leave it on quite often, bye-bye battery.

Turbocube

dwright,

Since I have read here that the PCM method of turning the aux fan on and off is connecting it to ground (the white wire, correct? ) when it deems necessary, I figured I would do a mod similar to yours, except that I would simply cut that ground wire, and splice in a wire leading to a 40A switch, which would in turn lead to ground via that fender bolt you mentioned. Like so:

FAN ---- SWITCH ---- GROUND

What do you think of this idea? I figure it would prevent killing the battery by using the alternator instead.

xjfirefighter

Don't have the link to the write up but I spliced into the harness and ran to a switch into the cab then grounded it to some sheet metal. Also tied in the extended idle to the same switch. Now when its in the "on" position I have a higher idle and the aux fan on in park when neutral. But when in drive just the fan. Perfect for wheeling

dwright98xj

hmmm, not sure turbo. My whole paln of attack was to resume it to service temporarily with the intent on putting back to proper function later on, so I did not want to hack into the stock wiring harness. You could double check your theory and ensure you have 12v at all times with a voltmeter. Again, I would personally make it a stand alone system for now.