Pressure control solenoid on 4T65E GM tranny

Maintenance/Repairs
1

I have a 2003 Buick Park Avenue with the 3.8L V6, not supercharged. Anyone know if the pressure control solenoid on the 4T65E transmission can be changed through the pan? I ask because I get hard shifting if the car is running in stop and go traffic where the engine cooling fans are starting to cycle. Simply shutting the car off and immediately restarting clears the hard shifting. Otherwise the transmission shifts smoothly. Searching the internet suggests the PCS is getting tired. I wouldn’t mind throwing a $50 part in as an attempt to cure this issue if the average Joe can swap it out.

2

The transmission side cover needs to be removed to gain access to the pressure control solenoid.

But here’s the part you’re not going to like.

IMPORTANT: The Transmission Adaptive Pressure (TAP) calibration must be reprogrammed with a scan tool after replacing the pressure control solenoid.

Tester

3

“Simply shutting the car off and immediately restarting clears the hard shifting.”

How does the solenoid fix itself? Seems like something else is going on. Any codes?

4

Apparently the hard shifting is the result of some sensor detecting a long shift. As a result, the pressure in the transmission is pushed to the max to prevent slipping. It maintains this high pressure until the car is restarted, then everything is reset to normal until it detects this long shift again. P1811 code is set. The suggestion is the PCS gets somewhat tired in its old age and could be somewhat slow due to built up varnish(?) in the transmission. Some people have had success using Seafoam trans tune-up. A description of the problem is here:


I should note that the transmission pan looked clean last summer when I changed the fluid and filter. Fluid was nice bright red and no sediment in the pan.

5

Not that I know much about it but if the side cover needs to come off, then its about a $400 job to drop everything out of the way. Been there. So might as well just have a shop do the whole thing and reprogram it again. A little more money but you can read a book while you’re waiting.