This is my last ditch effort to try and save this transmission. I’m not sure if I’ve mentioned this in the past but my GMC Envoy with 221k miles on it is starting to give me some issues with shifting. When you put the truck in drive from park, it slams into gear. Then when accelerating, the 1-2 shift is pretty hard as well. I’ve done some internet research and am thinking that this is an electrical issue. I’ve already replaced the negative battery cable to no avail, so onto something else. Being that there are no check engine lights, running a scanner on the truck reveals nothing.
After doing some research as stated above, I’ve come to think that the Electronic Pressure Control Solenoid inside the transmission is a possible culprit. All of the posts that have similar symptoms as mine seem to point to this as being the cause. Since it was a cheap part, I decided to replace it. While I was at it, I replaced the 1-2 and 2-3 shift solenoids. This is how you do it:
You will need to drop the pan on the transmission. This is covered in detail in this post.
Once you have the pan dropped, you will probably want to remove the filter from the transmission. I purchased a filter kit feeling that I might as well do this while I’m there. It comes with a Filter, new gasket, and the little round piece that goes up in the transmission.
Next, you will need to remove the accumulator assembly. Be careful, there is a gasket under the accumulator body that will tear if you are not careful….
You may just want to have a new one handy when doing this
job. There are 3 bolts that are holding
this in. Remove those bolts, I believe that
they are 10mm.
Remove the 8mm bolt that is holding the spring bracket to the Electronic Control Solenoid. Once the bolt is removed, you will be able to slide the bracket out of the grooves of the solenoid.
Remove the Solenoid and replace with the new one. Put everything back together the way it was,
as with most jobs, installation is the reverse of the removal.
Once you have finished with that, and if you were like me and purchased the shift solenoids as well, you can move on to replacing those.
Disconnect the electrical connections on the two solenoids.
You will need to remove the little clips that hold the solenoids in place. I was able to use a pair of needle nose pliers to pull the retaining clips out.
The shift solenoids will now just slide right out. Slide the new one in, put the retaining clip back in place, and reconnect the electrical connector. It’s as simple as that.
The rest of this job is just putting the filter back, or
replacing the filter, and putting the transmission pan back on.
Unfortunately, this did not solve my problem. The transmission shifts a little smoother,
but the problem persists. I just figured
I would post this in case someone diagnosed these parts properly and needed to
know how to do it.