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Discussion Starter · #1 ·
Hello everyone,

I have a 2007 Dodge Nitro 3.7L that stuffers from an overheating issue, i have recently replaced my head gasket (DIY) and didn't fix what caused the overheating to begin with (feeling kinda dumb) however today I scanned it and it came with code: (P0481 Cooling Fan 2 Control Circuit) done some research and check fuses and relays in TIPM and everything looks good, i have located the fan relay courtesy of @Nitrogen

Part number: 04707900A however if you search for it it shows something completely different (Chrysler Voyager Gearbox Relay) and I'm confused is this the correct fan relay?
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One more thing i noticed cracked insulation on the wiring harness at the fan shroud, is this fine or should i replace it?

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Your help is greatly appreciated!
 

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OverHeating from just sitting idling?

Overheating while driving/on the freeway?

You replaced the HG? OMG, did you have CO in your coolant? Usually a mechanic has to test for that.
 

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Discussion Starter · #4 · (Edited)
OverHeating from just sitting idling?
Overheating while driving/on the freeway?
I drove it for a couple of miles on highway and in traffic after replacing the HG and it runs smooth no issues, while driving back home in traffic temps started to creep up at a traffic light and reached the first quarter after the middle, i pulled over and turn it off and waited for it to cool down then drove it home.

Plugged my scanner and P0481 was present, while waiting for an input from the people here i went to junkyard and got a relay (the one in the picture) and plugged it in and ran it for half an hour to see if that fixes it so far the fan behaves normally turns on at 106°C and cools down the engine to around 100°C, I've yet to drive it and see if the relay was the issue or if the code would come back.

You replaced the HG? OMG, did you have CO in your coolant? Usually a mechanic has to test for that.
The overheating issue is not related to my new HG i believe everything is done correctly. My issue is definitely related to the electric fan or the relays in question.

As far as i understand this is a thermostatic relay and it seems to be overlooked by the most of the Nitro/Liberty owners.
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I would like to know if anyone's familiar with it and if it's good or if it can cause issues with fan's behaviour.
 

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when you switch on the AC do you hear the electric cooling fan switch on ?,
when the AC is on the high speed fan should always be running
the fan also runs at low speed with a seperate relay ( the relay in you pic could be for low speed fan) i would need to check the wiring diagram
 

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Discussion Starter · #6 · (Edited)
when you switch on the AC do you hear the electric cooling fan switch on ?,
Yes, but it takes a few seconds before turning ON and works for about 10-15 seconds then shuts OFF and continues in this circle.

when the AC is on the high speed fan should always be running
Do you mean High speed blower fan? I've only ran the AC on Level 2-3 while testing.

the fan also runs at low speed with a seperate relay ( the relay in you pic could be for low speed fan)
I've replaced the relay in the pic below with one i found in the junkyard and while testing the car in idle with AC OFF the fan kicks in at 106 C for few seconds then shuts OFF and does that every time it reaches 106 C and cools it down to ~100 C i was monitoring my temp on my scanner.

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Any ideas about the harness in the following pics? it seem like no one knows its function or if it could be the cause of the overheating issues, it's like a unicorn among the community.

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no i don't mean the blower motor,
the engines cooling fan at the radiator works on low speed and high speed so there are 2 relays,
if your cooling fan comes on at 106° then switches off after a couple of second maybe your temperature sensor is faulty normally the cooling fan is on for a couple of minutes not seconds ?
 

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Discussion Starter · #8 ·
the engines cooling fan at the radiator works on low speed and high speed so there are 2 relays,
I've checked the relay and fuse in the TIPM and they're both good. and as i mentioned i got the second relay that you mentioned in other threads (beneath the right headlight) from the junkyard and did the testing with it.

if your cooling fan comes on at 106° then switches off after a couple of second
it turns OFF after cooling the engine down to around 100 C not right away the fan stays on for 10-15 seconds. should it be running for few minutes despite lowering the temps to 100 C?

maybe your temperature sensor is faulty
Do you mean the ECT sensor or IAT sensor?
 

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Discussion Starter · #9 ·
A local mechanic suggested that this a thermostatic relay says it is responsible for sending a signal to turn ON the fan and could be faulty though I don't trust my local mechanics. can you confirm any of this?

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that last pic is the resistor for the high speed fan relay you can just ignore the resistors and the high speed relay for now, just reinstall them and forget about them they are not your issue,
when you run the engine upto temperature and the fan kicks in it is imossible for the cooling fan to cool down the engine in just a couple of seconds, it takes at least a couple of minutes,
i mean engine temperature sensor,
are you sure you have removed all the trapped air from the cooling system ?
how did you check the low speed relay in the TIPM ? although i'm sure it is fine,
in this order i would check for
1, trapped air in the cooling system
2, faulty thermostat
3, a faulty engine coolant temperature sensor
4, your actual cooling fan is faulty,
 

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Discussion Starter · #12 ·
when you run the engine upto temperature and the fan kicks in it is imossible for the cooling fan to cool down the engine in just a couple of seconds, it takes at least a couple of minutes,
That's what was happening while monitoring engine temps via my obd2 scanner, engine would reach operating temperature (106°C) as soon as temps reach 107°C i can hear and see the fan running for few seconds and notice the fast drops in temps from ~107°C to 100°C then it shuts off with my junkyard relay (i didn't do the testing with the original relay).

are you sure you have removed all the trapped air from the cooling system ?
I believe so, I've added coolant via the bleeder hole in the morning before starting the car, what's the best way to remove the trapped air in case there's air in the cooling system.

faulty thermostat
I've putted a new thermostat.

a faulty engine coolant temperature sensor
This might be something i didn't thoroughly check, I'll definitely look into it however keep in mind that i have a persistent code P0481 before disconnecting the battery which points towards something to do with the cooling fan circle. I believe if i could fix this could my random overheating issue would go away.

your actual cooling fan is faulty
Could be faulty despite spinning and doesn't make strange noises?
 

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Discussion Starter · #13 ·
@Nitrogen Sorry for the many posts, I've tested both relays (in the TIPM & behind the headlight) and i can confirm they're both working 100%

I'm going to test the socket on the TIPM and plugs to make sure both relays have power and let you know, i believe this way we can rule out my issue with the relays and focus on other areas.

Thanks for your engagement.
 

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pretty sure there is your problem the "new thermostat", several members on this forum have had issues with aftermarket thermostat,
simple test is to run the engine upto normal temperature, stop the engine and quickly check that both the top and bottom radiator hoses are the same temperature (very hot),
 
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