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Dave, Jeep Master Tech
Category: Jeep
Satisfied Customers: 1158
Experience:  Chrysler Triple Master, ASE master Tech AA degree in Auto.
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Automatic transmission won't shift. Do I need a new transmission?

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Automatic transmission won't shift. Do I need a new transmission or are there any other solutions to my problem?

Hi, I'm Dave, I would need a little more information inorder to help you.

What motor do you have?

Does it move at all in any gear?

Is the check engine light on?

What does the RPM's do when you try to drive it?


Customer: replied 8 years ago.
It moves on first gear it won't run past 20-25 miles per hour. and reverse.the rpm's just run up. yes the engine light has been on for a while but i was told that it was a selenoid or the gas cap is not closed all the way i believe it's a 4.0 liter

Hi, ok a 4.0L means you have a 42re transmission. and you are only getting first and reverse.

The check engine light is on meaning there are diagnostic trouble codes set in the computers.

You need to find out exactly what codes are set. You will need to find someone who has a code reader or a scan tool and hook it up and write down the codes (pxxxx).

I can guarantee you there are transmission related codes if it won't shift out of 1st gear.

You mentioned someone said a solenoid code. Do you know if it was a govenor solenoid code?

At any rate get the exact codes and let me know. We can take it from there then.

Thanks Dave

Customer: replied 8 years ago.
I live in Illinois, Would you know how can I find someone reliable with a code reader or scan tool? it was an ignition selenoid. I was also told that I could be that the transmission fluid might be clogged. could this be it? after I get someone with a scan tool it may take me a couple of days since I am going out of town but I will get back to you as soon as i get back thursday or friday the latest. I will apriciate your help on this matter.


Hi, I'll be happy to continue helping you out when you are back.

I have not run into a situation where the filter would be plugged and not allow the trany to shift. If the filter was plugged you would not get first or reverse either.

Other then bringing the vehicle somewhere to have the system scanned you can purchase code readers from the different auto parts stores. They are rather inexpensive and you have it for future use in all your vehicles.

Other then those two options the only other way would be if you know someone that might have one you could borrow.


Customer: replied 8 years ago.
Hi Dave,

I'm back from out of town, I took my jeep to a shop where they tell me that somehow water got into the transmision fluid, and that's what keeps it from shifting gears. Now this is the same shop that change the water pump on my car about a year ago. Is this any of it possible and if it is would it be related? like i mentioned before I'll appreciate all your help on this matter and I hope I am not being too much of a bother, but my main concern is not to get ripped off and making sure my jeep gets fix the right way. Please advise...

HI, I would not be to concerned over being ripped off. Changing the water pump would have no bearing on the transmission in any way. The only part of the cooling system that would have anything to do with the transmission is the radiator as the cooler lines for the trany go into the side of the radiator to be cooled.

You can verify the water in your trany by looking at the fluid on the trany dip stick. It should look like a strawberry milk shake if there is water in it.

Now the question is where did this water come from?

On a 42RE trany on the left side of the case you have the gear shifter and an electrical connector that come through the case. On the right side you have the fill tube. All should be sealed and not allow water to enter. You should have them checked to make sure they are sealed. The other way is if the radiator has an internal leak allowing coolant to enter the casing that holds the trany fluid. If this is happening you should be able to tell by looking at your rad. fluid. It again will look like a strawberry shake if this is happening.

Other then that the only way to get water in there would be if you poured it in through the fill tube or the trany got submerged in water.

Thanks Dave

Customer: replied 8 years ago.
lt;p>The radiator also has fluid in it. they tell me I'll be beeter oof re building the transmisson since they have to drain it all out and change all the seals and what not. they're going to charge me 1400 dls. does this sound about rught to you?</p><p> </p><p> </p><p>Thanks,</p><p> </p><p>Jorge.</p>

Hi, the cost is right. Make sure they replace the radiator too. I have had some success in the past with just replacing the radiator and flushing the transmission. It depends on how long has the coolant been mixed with the trany fluid.

You should also do a complete coolant flush to make sure you have all the trany fluid removed from the engine.


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