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Jumper for electric fan

R

robs

NAXJA Forum User
Searched but couldn't find anything...

Want to jumper my electric fan to a switch so it's on when I toss the switch.

Someone got a wire diagram or a how to?

hot.jpg
 
Trust me it's better to run it from a relay and have the switch control the relay. The previous owner of my 92 had it hard wired to a switch and to the batter and it burned through the harness under the hood and inside the dash.
 
This has been on my to do; list for so long and I keep putting it off ; \
I want to run a switch from the relay, being new to wiring I always decide to wait...
 
Your efan already has a relay wired in it's circuit by the factory - why add another? :dunno: Just use what you got. Depending on the year it's either triggered by a ground from the ECU (91 and above) or by 12V (Renix) to the fan relay coil. On my 91 I simply applied a ground thru a dash switch to the appropriate pin on the ECU to trigger the fan when I needed it. Does your efan come on by itself at 220* or so now? Do you have A/C and does it run when you turn the A/C on?
 
Before I hit the trail I jumper the sensor (RENIX) probably could easily wire a switch in as sensors usually run 5v, but I haven't DVM'd this one
 
Rockslut said:
Which pin is it on the ECU for 91 and newer? I would like to do this mod but have not had the chance to locate the correct pin.
Click to expand...

For the 91 and above ODBI ECUs it's pin 31. Easiest way for me to get to it was to take the shells of my ECU plug and splice my switch applied ground to pin 31. You can also pull up the PDC and splice it directly to the fan relay underneath.
 
My 95 ran hot at low speeds and I ran a switch on the e-fan. How I did it (which is probably not the best way---but it worked) is I pulled the relay in the box under the hood and used a wire to find which lead would turn the fan on (by running a wire from each hole to the battery until the fan turned on...IIRC it was the closest hole to the passenger fender) and ran the wire from the correct hole to a toggle and got power from the under dash fuse pannel and it worked.
Using this procedure, the fan would no longer come on unless the switch was on and would not shut off when the key was removed.

Like I said above, this is not the correct way to do this but it worked well for me for quite a while.
 
Jess said:
My 95 ran hot at low speeds and I ran a switch on the e-fan. How I did it (which is probably not the best way---but it worked) is I pulled the relay in the box under the hood and used a wire to find which lead would turn the fan on (by running a wire from each hole to the battery until the fan turned on...IIRC it was the closest hole to the passenger fender) and ran the wire from the correct hole to a toggle and got power from the under dash fuse pannel and it worked. Using this procedure, the fan would no longer come on unless the switch was on and would not shut off when the key was removed.

Like I said above, this is not the correct way to do this but it worked well for me for quite a while.
Click to expand...

Yep, you are right, this is definitely not correct. It appears what you did was apply 12V via your toggle switch to a fan relay load contact to trigger the aux fan relay. And by applying 12V to indiscriminately to the relay socket you could have smoked the ECU in your 95. :bawl: Control of the aux fan is to the fan relay coil via an applied ground by either the ECU or a dash switch.
 
Here is an easy way for you Renix guys with A/C to turn on the fan...

Pull the plug on the A/C compressor. Then put the HVAC controls into either A/C or Defrost. The fan will come on, and stay on until either the Jeep is shut off or the AC/defrost is turned off......

As for the newer ones, I have no clue.....
 
Hallo. I did mine '92 with a relay and thick wire from the battery .
The hot wire goes from the battery(+)(fused 20 A) to the relais pin 30. and from pin 87 to the green fanwire before the connector.
A bridge on the relay between pin 30 and 85. makes that you only have to contact a thin wire from pin 86 to a switch for earth in the cabin. Very safe and no hot wires with high current in the cabin.:laugh:
P.S. thanks to Magimerlin.
 
Last edited:
robs said:
its a 95. overheating is a way of life. radiators. head gaskets. high volume this high volume that. wetters. you name it. whats a pdc?
Click to expand...

Like someone said above, it sounds like you have other problems causing overheating other than the electric fan. I'm running two 10-blade OEM electric aux fans, no mechanical fan, and having no cooling problems. But anyhow, if you want to hook up a manual overide dash switch to turn on your fan in case you need it (like I did), use a single pole dash switch like the XJ rear window defrost switch, wire the normally open end contact to a good ground, then run a wire from the center switch contact and splice it to the wire on pin 31 on your ECU. This is for a 1991 ECU, but I believe the 91-95 ECUs are the same. To be sure, check for continuity between pin 31 and the aux fan relay coil in the PDC (power distribution center) on the right side of the engine.
 
I tried two OEM fans and it lasted one day. I have a factory 10 blade aux fan and installed a OEM 12 blade with a Flex-a-lite controller. Got the on off temp dialed in. Thing would overheat on the freeway almost instantly. Would heat up on the trail on long hills.

I have every single component new in my cooling system (95). Swapped the clutch fan and shroud back on and back to normal.
 
That's weird that it heats up on the freeway. I had that happen a few years ago when my cat was clogged. I use a Spal variable speed controller with the LO set at 205 and the HI set at 220 controlling the efan that replaced the mechanical fan. On the freeway the fan seldom runs, and if at all on a real hot day cruising at 75 or so it runs only sporatically on LO. The only time both fans run on HI is when stuck in traffic with the ambient temp 100+, and my gauge temp stays right at 210. I have also verified the stat housing temp with a laser thermometer and it is spot on with my temp gauge.
 
Well, my XJ is a little heavier than the average rig also. 2x4 bumpers with winch. OBA, D60 front, 14 bolt rear, H1 wheels with rubber runflats. I'm sure if I could dump 500-700 lbs it would be much happier. I also like to drive up the mountains at somewhat normal speeds. All of that together doesnt make for a very good combo.

My plans are for an aluminum radiator and high flow water pump. A mild stroker build would probably help too.
 
My rig is a long bed Comanche with a factory camper shell on it. It has a Hesco 4.5L stroker crate engine w. the Hesco hi-flow water pump, AW-4, and an aluminum single core radiator. The H2O pump and alum rad help out I think. I definitely noticed a difference when I swapped out my old GDI 3-core rad for the alum single core rad.
 
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