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mralexc, ASE Certified Technician
Category: Car
Satisfied Customers: 25
Experience:  ASE certified Master Automotive Technician, Vocational Degree in Advanced Automotive Technology, Nissan dealership training,
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Unlimited Rubicon: I have an 07 Wrangler Rubicon Jeep Unlimited

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I have an '07 Wrangler Rubicon Jeep Unlimited (4 door). I have had the software upgrade and have the Rubicon edition. The "hot oil" light has been coming on while four wheeling up a small steep grade crawling under 5 mph (on a road that I have successfully taken my dad's old Reliant K-car and other non-four wheeling cars. There is a grade but the two Jeeps following me (at the same speeds) had a external temperature gauge and we never registered over 165 on their vehicles. I had an external temp gauge and my transmission didn't register over 150.

I believe I have the stock added towing option to cool the transmission. How is it possible my "hot oil" light can even come on. I have taken this to two separate Jeep dealers that simply state all they can and will do is the software upgrade (which started this whole problem) and they've done nothing to help. Do I need a new transmission cooler? Are the after market deeper transmission pans like those from Rock Krawler a plausible remedy?

At this point, I purchased what I thought was my ultimate dream four wheeling machine and I cannot takek it four wheeling up short steep grades that I drove a K-car and Ford Escort wagon up my whole life.

Any suggestions? If this cannot be remedied, did Chrysler FIX this for the '13 Rubicon 10th Year Unlimited Wrangler? I'd prefer to fix my current Jeep if Chrysler could give me advice that one of their own mechanics would be willing to try. I'll try anything as it's cheaper than a new Jeep


James Benzmiller
hi my name is XXXXX XXXXX i am going to try to help you, well first of all i am sorry you are having such a time with your local dealership, you might wish to try to call Chrysler corporate.

i also looked up the repair procedures for a failure (reading high) for your transmission temperature sensor the dealership needs to attach miller tool #8815 to the TRS harness connector then check to make sure the resistance is under 5 ohms if it is replace the temperature sensor , they should do this under conditions that mimic your issue .

if the resistance is fine they need to measure the resistance of the ground circuit under the conditions if they have more than 5 ohms it is a ground issue

if the resistance is good they should check for a short to voltage still using the miller tool
if the voltage is above 0.5 volts then there is a short to power to be repaired

if no fault is found then the pcm needs to be inspected for faulty wiring or loose connector or high resistance to the temperature sensor following the wiring diagram .

I hope this is helpful the dealership should have the special miller tool and th flow chart i read is courtesy of Chrysler corp for improper transmission temp reading
Customer: replied 3 years ago.

That was done two visits ago and we were able to test it under similar conditions. With that gone as a possibility, do you have any other ideas?


The radiator, transmission, and all associated electronics have been checked at a total of four different dealer and yet the "hot oil" remains.


Chrysler put out a recent TSB, should my next step be an external transmission cooler (either factory or a B&N, etc..). Is there any plausibility of increasing the size of the transmission housing chamber (like those suggested in Rock Krawler) have a legitimate chance of working?


Sorry for forgetting the complete electronic diagnostics that the Jeep has been through multiple times.

Yes, it has a plausability if it is actually overheating but you said that you had an external gage on it and it read no more than 150 degrees that makes me think that there is a problem either in the programming or the temperature sensor, if it is not overheating it does not matter,

if it is overheating increasing the ammount of available fluid in the transmission to circulate will reduce the temperature of the transmission fluid. just make sure it is a quality part.

racers do this all the time you increase the size of an oil sump because you need to be able to store more heat because of the extreme use. but you are talking a small hill and on the highway with no load. and yes you can add another oil cooler i would recomend adding it after the cooler in the radiator to further reduce the heat back to the transmission.

i would seriously run another temperature sensor just in case so i could verify overheating

the only other things i could think of if it is overheating would be the lock up clutch or a restricted cooler line or the pump not moving enough fluid or extremely low fluid

i would hate to tell anyone to do something that i was unsure would fix their problem so i will say this if you are truely overheating and all electrical and flow tests and everything else the dealer has done comes back normal and it is just a bad design then yes adding another oil cooler and a larger pan will help but take this advice keep an external oil temp gage on it so you can watch the fluid temp because to cold of a fluid can be just as bad as to hot, you want normal operating temp.
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