97 auto to 99 auto transmission swap

[thegipper]

Some of you know I've been having transmission issues (stuck in 1st while cold). 97 V6 4x4 btw.

In the back of my head I know it could just be the transmission starting to fail so I've been keeping an eye out for a used one.

I found a 1999 Auto tranny with 104k miles on it for $300 which is a killer deal. Plus it's only 20 minutes from my house.

I'm debating if I should just buy it in case I do end up needing a new transmission.

My question is, will a 99 auto fit in a 97? I'm getting conflicting answers. When I look up transmissions on rock auto, I found this:

97 auto transmission (A340F) from trans authority has a part number of T500955

99 auto transmission (A340F) has two. "production up to 5/99 T500955(same as the 97)". "production from 6/99 T500956".

I can call the yard and ask for the production date, anyone know where it is located?

Also, what were the changes? Is it something major where they are not compatible or is it something simple?

Finally, should I buy it just in case I need it?

Thoughts?

 

[Chingpo05]

Some of you know I've been having transmission issues (stuck in 1st while cold). 97 V6 4x4 btw.

In the back of my head I know it could just be the transmission starting to fail so I've been keeping an eye out for a used one.

I found a 1999 Auto tranny with 104k miles on it for $300 which is a killer deal. Plus it's only 20 minutes from my house.

I'm debating if I should just buy it in case I do end up needing a new transmission.

My question is, will a 99 auto fit in a 97? I'm getting conflicting answers. When I look up transmissions on rock auto, I found this:

97 auto transmission (A340F) from trans authority has a part number of T500955

99 auto transmission (A340F) has two. "production up to 5/99 T500955(same as the 97)". "production from 6/99 T500956".

I can call the yard and ask for the production date, anyone know where it is located?

Also, what were the changes? Is it something major where they are not compatible or is it something simple?

Finally, should I buy it just in case I need it?

Thoughts?

I should fit all the way up to 01, 02. I have a 98 on my 00 due to a planetary gear failure, common on the 00 +

 

[thegipper]

Also, does anyone know if there are any band adjustments on these transmissions? I know my 97 ZJ had bands that could be adjusted on the transmission which affected the way it shifted, I'm not sure that even applies to the A340F. My understanding is there isn't bands because it is electronically controlled?

I've read others on here who said 96-00 auto's trannys (A340F) are all the same. At the same time, on Rock auto they have those two different ones for mid 99 and up?

Anyone else have any rock solid info to provide?

 

[TheDurk]

The production date is on the tag on the driver door jamb.

As to slushboxes, I can't help, except the electric part, if you get there.

 

[thegipper]

The production date is on the tag on the driver door jamb.

As to slushboxes, I can't help, except the electric part, if you get there.

I may drop the pan (again) and test the solenoids even though there isn't any codes at all.

I just called the yard and the dang tranny just sold like an hour ago. That stinks, that would have been a good deal.

Tranny still shifts perfectly fine but stays stuck in 1st until warmed up. So annoying..

 

[thegipper]

The production date is on the tag on the driver door jamb.

As to slushboxes, I can't help, except the electric part, if you get there.

I forgot to ask Durk, do you know what the resistance should be for the solenoids? I believe there are three, two for shifting and one for TC lock up.

Thanks

 

[phattyduck]

I have a '97 trans in my '99 and it works perfectly. '96-'00 should be externally compatible. The valve body and possibly other internal parts are different, but it will be a plug-n-play swap if you do the whole trans.

-Charlie

 

[LookAtThatDog]

Also, does anyone know if there are any band adjustments on these transmissions? I know my 97 ZJ had bands that could be adjusted on the transmission which affected the way it shifted, I'm not sure that even applies to the A340F. My understanding is there isn't bands because it is electronically controlled?

Theres a cable from the throttle body off to an electrical box that tells the trans when to downshift and stuff. Maybe check it for slack? It can be adjusted super easily where it attaches to the TB.

 

[thegipper]

Theres a cable from the throttle body off to an electrical box that tells the trans when to downshift and stuff. Maybe check it for slack? It can be adjusted super easily where it attaches to the TB.

The cable is adjusted fine, plus it only controls line pressure not shift points.

Thanks though

 

[thegipper]

I have a '97 trans in my '99 and it works perfectly. '96-'00 should be externally compatible. The valve body and possibly other internal parts are different, but it will be a plug-n-play swap if you do the whole trans.

-Charlie

If I do replace the trans, it would be an entire swap. What about the transfer case, any issues/changes with them or would it bolt up to a 99 just fine?

 

[phattyduck]

The transfer case deal is a separate issue. There are a few different transfer cases, depending on year and trim... Worst case, just bolt your stock one on the new (to you) trans.

I went from 2WD to 4WD with the trans swap... so I had a different set of transfer case challenges. :wave:

-Charlie

 

[pauldub]

Solenoids should be 11-15 ohms and there are three of them. My Cherokee had the same tranny and when I had symptoms similar to yours, one of the solenoids was bad. You can dig through the FSM to find a connector where you can check the resistance without pulling the pan off.

Just give in and check the solenoids, you have nothing to loose.

 

[thegipper]

Solenoids should be 11-15 ohms and there are three of them. My Cherokee had the same tranny and when I had symptoms similar to yours, one of the solenoids was bad. You can dig through the FSM to find a connector where you can check the resistance without pulling the pan off.

Just give in and check the solenoids, you have nothing to loose.

I tried finding where the connectors are on the outside of the trans for the solenoids but couldn't find it.

Pulling the pan off really isn't that big of a deal, I've have to do twice this year alone. Plus I have a rubber gasket on which makes it even easier, screw using FIPG....

When I had the pan off the first time this year was because the filter/screen was plugged with brown gunk. There was also this gunk on the bottom of the pan. I am starting to wonder if this same gunk isn't messing things up inside the valve body. The pan was otherwise spotless, not a single metal shaving and the fluid was still looking brand new.

If its not the solenoid, it may be the valve it self could be sticking because of this gunk until the fluid warms up a bit. So, the solenoids may actually be fine and a ohm test may say they are fine (because they are) but the valve itself is boogered up. Or maybe when I check the solenoids they will test bad but with my luck, it won't be that simple.

I'm really hesitant to try a power flush but what I did do was put some Seafoam trans tune which is supposed to clean out the gunk and free sticky valves etc. At this point, I'm willing to try anything. I'll know tomorrow if it worked or not.

As far as the transfer case compatibility, I'll have to research what years had different transfer cases than a 97. *****never mind, I would be using my old transfer case which should bolt up to any compatible tranny I would be using.

 

[thegipper]

If the seafoam tranny stuff does clean out the valve body and fixes my issue, I'll be doing a total fluid exchange to get all of the seafoam stuff out.....

And the lucas tranny stuff out.....

And I'll actually put some high quality fluid in it......

Maybe I'll splurge and run the Amsoil signature series fluid like I do in my other Yota's.

 

[pauldub]

Since you found gunk in the pan, I'd consider pulling off the valve body and cleaning it. Take all the valves out of the body, soak everything in solvent and blow out all the passages with compressed air or carb cleaner.

 

[thegipper]

Since you found gunk in the pan, I'd consider pulling off the valve body and cleaning it. Take all the valves out of the body, soak everything in solvent and blow out all the passages with compressed air or carb cleaner.

This would be my last option. I have to admit I'm rather terrified of removing the valve body. I've never done it before and I'm under the impression when I remove it, balls and springs will shoot everywhere (ok I'm exaggerating a little).

I wonder if there are any good write ups on this other than the FSM.

 

[phattyduck]

There should be a good write-up on an A340 shift kit install somewhere... *If* you have to go that far.

-Charlie

 

[thegipper]

Well guys, I have some very promising news. I will update my main post so this one should be not needed (fingers crossed). I dropped the pan to inspect/test the solenoids. Lock up solenoid ohm test, pass. 12v power test to hear audible "click" passed. The middle solenoid, ohm test pass, 12v power test passed, audible click so it passed.

When i removed The final solenoid (I believe is the 1st gear shift) I immediately noticed something. I could feel and hear something rattling in there. The others did not do this. Plus the housing looked "burnt" or darkened in the center. Here is the crazy part (which makes sense), it passed the ohm test (probably why it wasn't throwing a code but totally failed the 12v power test. No audible click, just a mild spark on the connector when I would give it power.

Looks like I need a new solenoid!

Fingers mega crossed

Here is a video of it. https://youtu.be/t0o_WlacJ-o

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