fit a 1994´transmission in a 1999´Seville STS?

[Jens]

Hello,
my name is Jens from germany. I´m driving a 1999 Cadillac STS Northstar and have a broken automatic transmission.
Know i can get a automatic transmission from a 1994 Cadillac STS Northstar. Will this transmission fit into my 1999 Cadillac?

It is not easy, to find a used transmission here in germany.

Thanks for your help.

Jens

[Caddyshack100]

They 'should' fit together, but a 94 is from obd1 and your 99 is from obd2, which means your pcm will not communicate with the older transmission. It would be better if you sent to North America for the tranny, it may be your only choice that will save money in the end. Lastly, are you sure the tranny is 'broken' it may need a solenoid or something else that is replaceable. Good luck

[Jens]

thanks for the answer.
Sending to North America is much to expensive from germany.
I have the 1994 transmission for free and it is in a good condition.

What must i change, that the transmission will fit into the 1999? Only the electronic parts?

Jens

[Ranger]

What is wrong with your transmission?

[Caddyshack100]

Jens, you need to tell us what brought you to the conclusion that you need a transmission, it is not as simple as just changing electronic parts, a 94 transmission may not have the same amount of electronic components that a 99 did. Even if you were to change the electronics, some of them may be buried in the transmission itself, forcing you to open it up. It may still not work properly with the PCM. Another less expensive option might be to have a transmission rebuild kit sent over to you and have a mechanic rebuild yours. Did any codes come up and what were they? Unless you have had a big bang in your transmission, it is possible that you do not need one at all. You may just have to replace parts that are known to go on these Transmissions. Also how many km do you have on the vehicle?

[Jens]

it was a big bang when i was driving, know the cadillac is only using the first and second gear, no third and fourth, it seems to be the "overdrive".
My cadillac has 130000 km = 80000 mls on.
The transmission from the 1994 has only run 40000 mls, it is from an accident car.

[Caddyshack100]

Jens, these Transmissions are really good units, from what you have said, it sounds like one of the transmission solenoids inside has failed. This is a common problem and yours has hardly any mileage on it. Check first and see what codes come up, if your tranny did dynamite then your pcm should have codes stored. It is possible that the solenoid that controls the 3/4 shifts may have gone south. You can do a search on the site and see for yourself if what they are talking about relates to you.

[Jens]

That is, what i´m missing. There is no trouble code in my pcm. I double checked it with a Tech II-Tester for OBD II by an officially cadillac dealer here in germany.
That is why i´m thinking, there is a mechanical problem with the transmission and not an electrical problem.
I have the 1994 transmission for free, so i thought, it is the best way, to change the transmissions...

Thanks for your help and please excuse me for my bad english

[Ranger]

I think I would drop the pan, pull the valve body and inspect the solenoids. A repair kit is only about $50. I wish I could tell you if the '94 & '99 is compatable but I am not sure. Chevell or ewill3rd would know, if they read this thread. I'll try to contact them for you.

P.S.
Your english is better than some American posters.

[Jens]

that would be very nice. I don´t know, who can i ask here in germany. They all want to sell me a new transmission for over 4000,- $

[ewill3rd]

I might be able to look into this.

The '94 trans might work.
OBD II doesn't really matter, the transmission only has solenoids in it, not electronics that communicate. The PCM controls the trans and they both have the same connection.
I can't really think of a difference. It should be the new design N* engine with the plastic cover on the engine instead of the metal plate cover.

Remind me and I'll double check.

I never make fun of people who speak two languages.
I can assure you that your English is better than my German!
I can't say much more than hello.

Like Bruce Willis said "I only speak two languages... English and Bad English!"

[Ranger]

Here is what Chevelle had to say.

"As best as I can recall a 94 4T80E should work fine in a 99 model. The OBD stuff doesn't really affect the trans. Deals like this are always tough because there may be some detail I can't recall off the bat about the compatibility of the two but I am reasonably sure the 94 would work fine. The main thing is that they are both from an STS from what he says so they both have the correct gearing....that is what is important."

[Jens]

Thanks for your big help. This forum here is great. I´m very lucky, that i found this forum.
I checked the gear ratio, it is the same. Also the option codes from the vinnumbers are the same.

When some of you is in germany, then you are absolutly welcome in my house.

Jens

[ewill3rd]

The really haven't changed the 4T80 much over the years.
As the other person said, the only real difference might be the final drive ratio.
If it's the same RPO then it should realistically be the same.
If they both have the same connector on the electrical harness then I almost don't see why it wouldn't work.

If you'd like me to take a few minutes I can get out the manuals for both and compare the wiring harnesses and connections.
Be warned, I'll forget as soon as I close this window and I am pretty busy these days.
A reminder post would really help if that's what you'd like.

[Jens]

sure i would like to have it. If you need both vinnumbers, here they are:

1999 1G6KY5499XU939192
1994 1G6KY5298RU843866

Thanks alot.

Jens