• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Fan override switch 97+ models

Purple

NAXJA Forum User
does anyone know how to make one? I know XJ-Armor sells it, but that guy is a jackass and i do not want to deal with him. Heard too many bad words about him. Anyway, i need to know where to splice the wires, etc... Thanks.
 
yeahh, i found that on google:( it will not work wirh 97+ models, Thanks Anyway
 
Fan Over ride switch, as in turning on the fan before the temp sensor does?
IF that's the case just wire in a switch and relay. Mind the current draw on the fan. (Use 10 gauge wire on the primary side of the relay)
I wired a toggle in to bring the fan up for the tranny cooler if needed before the temp sensor turned on the fan. Since I by passed the radiator and installed a bit of overkill on the tranny cooler, I haven't needed it, tranny stays cool all day long. But it (the switch) works.
01 XJ.
 
i understand, but what about the connection for the fan, the stock one, how do i wire in the switch and relay, so when i flip the switch to "on" the stock connection will get "disconnected" so no power goes to the stock control box/computer ...?
 
lets say, its ....+15 C. and i dont want to run ac... just the fan...
 
In '97+ models, the aux. fan is negative switched. The general consensus seems to be to leave it alone, due to the ECU being involved. It, the ECU, would need to be isolated by relay or, I suppose the better way might be that a diode could be used to prevent current from getting to the ECU. I'm still looking for an acceptable way to do this, too.
 
i will ask my friend HAM to solve this for me, what if the fan is operated manualy , and ECU Neg voltage kicks in? what will ECU get? will it get some kind of code that the fan does not respond or something?
maybe an additional fan would be the resolution? i have looked at the space between the grill and my ac/radiator cores, there is about ... hmm..2 inches?

I dont understand how somebody on ebay can be selling something like that, and there is no diagram on NAXJA how to come up it.
 
Last edited:
I did away with my factory fan, put in 2 electrics and wired them up to a double pole relay. one pole for each fans positive. I am using a thermostatic switch, and the original fan power wire to power the relay coil. no adverse effects, but I am only using the positive side of the fan circuit, and it is grounded straight to the battery.
 
I'm not sure how XJ Armor can claim it will work for '84-'01s because the circuits are different. I would think using it in a '97+ would trip the ECU and check engine light. Not sure, though; I know just enough about electronics and schematics to get myself into a good amount of trouble.
 
I used the wiring harness that I bought used from a set of Piaa offroad lights (rated at 100W)-relay, switch. Connected the switch to relay, power from fuse box and splice the wires to the aux. fan (above the plastic connections). Works everytime I turn on the switch. No codes, no check engine light, no other problems that I can tell. Over 2 years now. I'm no expert at wiring stuff up-just letting you know what I did.
 
Sorry,
2001 AW-4 Limited 5.5RE ARB Front & Rear Teraflex HP60 CRD Rear, Teraflex HP44 CRD crossover steering, Atlas II 3.8.
 
jxj,but if you did that, and battery power is connected to the fan, just above the plug, doesnt that transfer power to the harness, when you turn it on? What i wanted to do is install two relays in that circuit, one for the fan, and the second one would disconnect the stock fan wiring...
as for the check engine light, it does not come on when fan disconnected, tried that right now.
 
It is simple, if it is switching ground. You would use a SPDT switch (Single Pole Double Through), contect the wire from the fan ground to the center pole then the wire that feeds the ground to the fan to the upper pole then any ground sorce to the lower pole. What you now have is in the switch up position the fan would be on, and isolated from the normal ground feed to the fan so the the computer would not be effected. With the switch in the down position it would work like normal. The only thing that might be an isse is when the computer wants to turn the fan on I don't know if it checks to see that it is accualy seeing curent returned through that line. It should not. This will be the safest way because there is no way to have it off if the computer says it needs to be on, it is ether controled by it or is already on.
 
XJJack said:
It is simple, if it is switching ground. You would use a SPDT switch (Single Pole Double Through), contect the wire from the fan ground to the center pole then the wire that feeds the ground to the fan to the upper pole then any ground sorce to the lower pole. What you now have is in the switch up position the fan would be on, and isolated from the normal ground feed to the fan so the the computer would not be effected. With the switch in the down position it would work like normal. The only thing that might be an isse is when the computer wants to turn the fan on I don't know if it checks to see that it is accualy seeing curent returned through that line. It should not. This will be the safest way because there is no way to have it off if the computer says it needs to be on, it is ether controled by it or is already on.
Actually both circuits use the same ground. What you described above is wiring a fan switch in parallel with the stock E-fan controls. As long as you use a relay so you don't run 30 amps to the switch it will and does work fine.
Remember the ECU doesn't turn on the fan, but energizes a relay that turns on the fan. The relay isolates the stock circuits, ie, when the fan is on you will not put 12 volts back to the ECU or the A/C high pressure switch as an example. And when the ECU tells the fan to come on the circuit paths are in parallel resulting in the sma evoltage across both ciruits and hence no adverse potential differences to stock wiring or components.
 
482928_45_full.jpg


Very easy to do as mentioned above with a SPDT relay. I made this little sketch about a year ago when I did it on mine- I use it frequently and it has worked just fine. (the little round thing is a toggle switch) Fan functions normally when the switch is "off" and on full time when in the "on" position.

Piece of cake

oh and that !2V should be 12V (stupid sticky shift key)
 
Back
Top