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BigTicket13 11-27-2011 12:22 PM

Fan Relay Problem
MY buddy has a 2004 4.0 WJ and the fan will not turn on. We have located the relays under the hood in the fuse box, but we also heard there is one undere the passenger headlight unit and requires drilling to make accesible. Any suggestions?

Frango100 11-27-2011 12:34 PM

Re: Fan Relay Problem
As far as i know the 2004 4.0 model doesn´t have the relay under the passenger headlight anymore. Instead of this, they use 2 separate relays in the PDC. the high speed and low speed relay. Did you check the fuse for the fan already, its # 10, 40A in the PDC.

BigTicket13 11-27-2011 12:57 PM

Re: Fan Relay Problem
Yes that 40A fuse is good. How can we test the relays both of them. Also we were pondering that if the TSTAT isn't operating correctly could that cause the relays not to turn on. As in its not telling the vehicle it is to hot.

Cause we filled the radiator and after five minutes of run time it just keeps flushing back into the over flow.

I say replace tstat and test fan to make sure its work and hopefully figure out a way to test the relay as well.

FYI its 04 WJ 4.0 with 180,***

Frango100 11-27-2011 03:57 PM

Re: Fan Relay Problem
I don't know the 4.0 setup, but i think that the temperature sensor is in the engine cooling circuit before the thermostat, so thermostat position should not have influence. Is the system properly filled with the coolant and is all air bled?
There is an other control fuse on the junction block of 15A, only don't know the position number.
You could check the fan by removing the HI-speed relay and interconnect point 2 with point 8. Take care not to contact any other contact point. You could also do the same with the lo-speed relay, here you only connect point 30 with 87.
Here follows the fill procedure from the manual:

(1) Tighten the radiator draincock and the cylinder
block drain plug(s) (if removed).
(2) Fill system using a 50/50 mixture of ethyleneglycol
antifreeze and low mineral content water. Fill
radiator to top and install radiator cap. Add sufficient
coolant to the reserve/overflow tank to raise
level to FULL mark.
(3) With heater control unit in the HEAT position,
operate engine with radiator cap in place.
(4) After engine has reached normal operating
temperature, shut engine off and allow it to cool.
When engine is cooling down, coolant will be drawn
into the radiator from the reserve/overflow tank.
(5) Add coolant to reserve/overflow tank as necessary.
Only add coolant to the reserve/overflow
tank when the engine is cold. Coolant level in a
warm engine will be higher due to thermal
To purge the cooling system of all air,
this heat up/cool down cycle (adding coolant to cold
engine) must be performed three times. Add necessary
coolant to raise tank level to the FULL mark

after each cool down period.

Gus9890 12-01-2011 12:29 PM

Re: Fan Relay Problem
I have an '01 Limited, my relay is located behind the passenger side wheel well, you can get to it just by turning the wheels to the right. I replaced mine because the fan wouldn't shut off, it was rather easy and haven't had an issue since.

merwin10 12-01-2011 02:19 PM

Re: Fan Relay Problem
Have you checked the ECT sensor! That is what tells the relays to come on in the first place! Mind was open and the fan would not come on and of course engine was hot as hell! Check your codes P0118 is the error! (on - off/on - on/off -on) code will come up in the odometer! If it is the same as mine! Two minute fix!

Mike -

BigTicket13 12-01-2011 06:53 PM

Re: Fan Relay Problem
The fan motor actually went on it. So we replace that and the tstat for 12 dollars you can't go wrong. So that fixed that problem. FYI the relays where in the fuse box located under the hood on the passenger side, top two closest to the firewall. Wasn't really a bad fix at all. Thanks for your guys help the buddy thats jeep it was is now a member on here. (NO INFLUENCE BY ME LMAO)

tommc4 12-03-2011 05:23 PM

Re: Fan Relay Problem
I have gotten a LOT of advice, info and help from you fine folks here, so I am happy to be able to provide a bit myself!

I had the same issue with my '03 GC. My brother owns a tranny/gen repair shop, and came up with a great idea. he pulled the headlight, and took a Dremel with a saw blade, cut through the plastic, to expose the fan module. 10 minutes to cut, 5 to swap the module, put the headlight back in, and everything is running perfectly.

Beats the hell out of pulling the bumper! Has been like that about 8 months now, been through a hurricane, heavy storms, etc, and the module still has yet to see water hit it.

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