my friend and i changed the tranny in his '99 bravada b/c it lost 3-4 gears. well the tranny we put in shifts hard from 1-2 when you drive it for a while and it gets up to operating temperature. its fine when its cold. i did notice that the temp gauge barely gets over the 100 degree mark even when its warm. We think that the valve body may be bad? or could the temp guage be causing this issue? I searched for a how-to on changing the valve body but haven't found one. is this a pretty hard job seeing how i have never done this before.

Thanks for all the help in advance,

dustin

 

Sooner or later I bet you will get a P1870 code if the problem is left unrepaired.

Many mechanics will tell you that the trans is bad and needs to be replaced or rebuilt. If you have a high mileage trans, then they may be correct. However, that probably isn't the only problem.

The real reason for the problem is the valve body and it needs to be corrected. If caught early enough in the life of the trans it won't cause too much damage. The TCC regulator valve is the likely cause for the harsh warm 1-2 shift. The Sonnax TCC Valve Regulator Valve Kit (CLICK HERE and scroll down to just after 43G as an example of a source for this part).

There are used to be two different Sonnax kits available, but it looks like they have consolidated it down to the following PN:
Sonnax #77754-04K - 93 & UP including EC3 - 4L60E (~$46)


To do this repair correctly - you need to find a shop that has the correct Sonnax Reamer (#7754-R2) to correct the valve body problem and replace the TCC regulator and sleeve with the updated parts.

The valve body can be dropped without removing the transmission and some shops may ream out the TCC bore for you with you removing the valve body.

Now, back to the earlier comment about the transmission being rebuilt and that it may not cure the problem. The valve body is typically overlooked in a general rebuild. If that happens, the problem will likely reoccur.

There is a lot of information about the 4L60E available on many different websites. You can even find videos showing shift kit installations around on the net. There are even new, updated valve bodies available from a number of retailers if you wanted to go that route instead of reworking your current VB.

Another thing that I would suggest doing while you have the VB out is to install a shift improver kit and a new separator plate. Well worth the time and effort.

 

yea, i forgot to mention that its throwing the p1870 code. the tranny isn't rebuilt but it doesn't seem to be slipping and it has all of the gears. It's only been driven about 60-70miles since we installed it. Is there gonna be springs and a bunch of other junk thats gonna come flying out when i take it off or is there just gonna be the check ***** and a gasket?


Thanks,


Dustin

 

IIRC, it will only be the check ***** that you really have to worry about, but you do have to be careful not to damage the wiring harness. Once you get to the point of removing shift solenoids, etc, there will be some springs and spool valves, however they will not come shooting out at you.

 

Well we took the valve body out and installed the sonnax parts and it seems to be better, Still shifts firm but it doesn't change with the temp of the vehicle. its not nearly as hard as what it was before its way better now. The funny thing is that the 1-2 accumulator was assembled backwards when we took it apart. The SES light hasn't came back on yet. What will happen when the 1-2 accumulator is put together wrong? Just Curious.

Edit: We ended up buying the reamer.

thanks, Dustin

 

Well the harsh 1-2 shifts are back and the SES light is back on. i'm gonna check the code and see what it is but i'm betting its the same as before. What about the lock up soleniod? would that cause this issue? we used the VB out of the other trans and all of the solenoids except for the convertor lock up solenoid.

 

Sounds like there were more issues in your trans than the sonnax repair kit could cure. This is one of those cases where you were damned if you do, damned if you don't. Sounds like your trans is on its way out.

 

Yea i'm not gonna give up on it that easy though. I'm gonna check the TCC solenoid and make sure its working correctly also. I think it might be part of the problem also. I'm not convinced that its bad yet. Cant feel it slip or anything when you drive it. Gonna check the line pressure too see if theres a leak anywhere. Just not convinced yet thats all.

Advice is always welcome and much appreciated though. I will keep you all posted on the progress though.

 

I'm having the same rough shift from 1st to 2nd also.
And I have been pondering what to do also.

Although I do not have any codes that come back (recently) or ses light.

 

well the tcc valve in the Valve body is the first thing to check b/c that is one of the known problems. there is actually a update for it. the parts are about $40 and the reamer is about $85. I ordered a lock up solenoid that will be what i do next when it gets here.

there is really only three things that will cause this to happen. the tcc valve in the VB, lock up solenoid, or bad torque convertor.


If the torque convertor has gotten hot it will have a blue color to it (it will be noticeable).

the P1870 code is a generic code but what it means is that the rpms between the tc and the output shaft are different. the light will come on if they are 130-800 rpms different from each other. thus the pcm makes the pump run at max line pressure.