At what temp should the E-fan come on? All I have on my cluster are idiots lights (for now) so I don’t know what temp I’m actually running at. I’ve only been able to run it at idle due to having a brake rebuild in progress. I’ve also have reved it up for quite some time to try to get the fan to activate. The hoses seem to be extremely hot, but no E-fan running. I know the fan works as I have tested it. Not so sure my temp idiot light is working either. It’s an 89 with 4.0

 

117°F, IIRC. Do you have an infrared temp gun you can verify the coolant temp with? I put a single sheet of newspaper across the grille to block the airflow from the mechanical fan while it idles. The fan suction keeps it in place unless it's breezy out. That's my trick for getting the coolant temp safely high enough to kick on the e fan.

 

217.

 

Isn’t 117 f very low? I pretty sure the thermostat is opening at 195. Is there that big of difference between the temp at the radiator temp sensor? I will block the air flow like you said and see what happens. No I don’t have an infrared gun, but maybe I should invest in one. Thank you for your reply.

 

217 degrees, thanks Downs

 

He meant 217. I'm saying 215, but let's not get picky. I've been told, although I haven't looked for it yet, the thermostatic switch to turn it on is on the side of the radiator next to the lower hose.

 

After you posted 217 I figured that’s what he meant. I hate having these idiot lights. Been trying to find a new gauge cluster. I plan on adding a switch to run the fan in addition to the automatic feature should I ever need it.

 

Yeah, 217. Brain fart, sorry.

 

Many rock crawlers do exactly that. Install an over-ride switch so they can make the e-fan run constantly whenever they are going slow and it heats up.

 

I’ve been looking at an over ride switch set up from K Suspension that seems to be exactly what I want. I still need to get a infrared temp gun to try to get a good reading at the temp sensor at the radiator. I put a new sensor in it when I swapped out the closed cooling system to open. But the fan didn’t come on before the swap either. As I mentioned before, I know it works because I bench tested it when I did the cooling system swap. It very well be that it’s simply not reaching temp due to the fact it’s in dire need of new brakes so I’m limited on putting any good distance on it. I will block the grill and see if I can heat her up more. It just kinda worries me that at the moment I have no idea how hot it’s getting (stupid idiots lights) and would hate to damage something.

 

I've had an e-fan override on every Jeep I've had. Really easy to wire up. Not sure what the procedure is on Renix Jeeps. Up to 97 it's a switched ground on 97+ I think I had to wire it up with a relay and power can't remember exactly.

 

There is another cool function built into late model XJs in the police versions called an "extended idle switch." This is designed to raise the idle to 1000rpm in neutral or park to keep the alternator on-line to keep up with the draw of their radio equipment. On these models, there are 4 switches in the panel below the heater panel instead of 3. You can put a switch anywhere you wish if you don't have the stock one. All it does is ground one wire from the PCM. This is the grey wire that comes from cavity 12 of the "A" plug (the one closest to the firewall) of the PCM. Ground it and the idle jumps to 1000. Unground it and it returns to normal of about 600-750 rpm. I'm pretty sure this only works on Chrysler systems and not on Renix.