HELP ! Problème 545rfe Grand cherokee

Jeeper45 · **Joined:** Sun Dec 18, 2022 4:48 am **Posts:** 6

Hi there,

I bought with my wife a 2006 Grand Cherokee the HEMI V8 equipped with a 545RFE transmission, but the box was broken, so we bought it and we started to look at the problem more closely, we changed the gearbox by a second-hand gearbox in good condition. After a few kilometers the transmission started having strange reactions again. So I thought about it and said to myself that it was transmissions known to be strong and that it could come from the car, something that damaged the transmission. The car was running very well and at all speeds the problem was when we stopped to fill in gas for example and then restarted it was spinning hard. So by dint of looking we found the cause! It was an oil cooling problem, it is done on this model by the air conditioning condenser, we did not have air conditioning in the car so the transmission oil rose in temperature and even more when the vehicle was hot and when stopped so it caused slipping etc.
We therefore changed the air conditioning condenser, completely drained the box and filled the air conditioning circuit with gas and also the transmission oil, the transmission no longer overheats as before, but we have a new problem. When switching from 2nd gear to 3rd gear, the transmission resets to 1st gear! I changed all the sensors (2 speed sensors and 1 pressure sensor) and I think it could be dirt or deposits that got into the valves or solenoids, so I'm going to take them apart and clean them this afternoon. . What do you think ?? Have you ever had this shifting problem?
Thanks a lot for your answers.
Goodbye

I hope the translation is not too complicated.

WWDiesel · **Posted:** Sun Dec 18, 2022 1:10 pm

Did you replace the two filters inside the transmission pan when you changed the fluid?
If not, you need to do so since the fluid had been overheated.

Problem could also be a problem with the solenoid pack, you may want to consider changing it out with a new one. Be sure and use the same color, white, gray, etc...

Also note: This transmission is a big transmission and is most happy when slightly overfilled with fluid. Most run an extra quart over the full mark when hot.
And lastly, ONLY use ATF+4 transmission fluid in this transmission, anything else can cause all kinds of issues.

If you continue to have transmission overheating problems, you should add an auxiliary transmission cooler to help supplement the cooling capacity of the OEM factory cooler.

SOLENOID PACK

Jeeper45 · **Joined:** Sun Dec 18, 2022 4:48 am **Posts:** 6

Good evening,

First of all thank you very much for your answer!
Yes yes of course, I changed the two filters and I also completely disassembled and cleaned all the valve body, it's only the solenoids that I didn't actually change... I'm changing the solenoid pack on Thursday .
Since we repaired the air conditioning we haven't had the transmission overheating problem like before, at least not for the moment. I'm going to think about adding an additional radiator for the transmission to prevent future overheating problems, thank you for the tip!

I only use ATF4+ from Mopar, I also replaced the crankcase gasket which was in paste with an already formed seal because apparently the paste and the ATF do not get along.

I didn't know about the extra liter! Good idea if it helps the transmission feel good thanks!

Once the box is repaired and will be fine, I plan to do a complete oil change after a hundred kilometers to be sure that there is no debris or old oil left in it.

Thank you again for your answer !

WWDiesel · **Posted:** Mon Dec 19, 2022 4:45 pm

Tip:
When you R&R the pan to replace the solenoid pack, please consider using a LubeLocker transmission oil pan gasket; they are by far the absolute best transmission pan gaskets that I have ever used on a vehicle and the best thing is they are reusable.
The gaskets have silicone rubber built into the gasket, see picture.
They also make differential cover gaskets as well. I have upgraded all my vehicles to their transmission pan and differential gaskets and now everything is dry and leak free. :BANANA:

Jeeper45 · **Joined:** Sun Dec 18, 2022 4:48 am **Posts:** 6

I'm ordering one right away!
Thanks for the advice, that's really nice!

Jeeper45 · **Joined:** Sun Dec 18, 2022 4:48 am **Posts:** 6

Hello,

I just changed the solenoid pack and still the same problem...
I was told that the box could have overheated and no longer work and that it would have to be changed but I have no slippage or downshifting problem.
I'm going to try right away to change the gearbox calculator but I don't know where it could come from if it's not that...

If you have any other ideas, please let me know.

At this time the body valve has been cleaned, the solenoid pack has been changed, the speed and oil pressure sensors have also been changed.
But the gearbox heated up several times before the transmission oil cooling problem was solved.

HELP ! Problème 545rfe Grand cherokee

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