Transmission (?) hard shift - turn off - then OK,,,?

[polo]

Ever since I had the already discussed disastrous service from the GM dealer (transmission flush, radiator flush, oil change, etc...)...

My car has intermittent hard shifts (transmission?)...

It seems to start when the car has been running for awhile - whether it be idling for quite awhile in a long line at a fast food drive-thru waiting in line - or when driving it for a longer period of time...

The car will start to hard shift - but then if I turn it off for about 10 seconds and then turn it back on - it runs fine...

Any ideas...?

Thanks!

[harofreak00]

You have a P1811 code.

From: 2000+ Common Problems & Solutions (updated 5.11.11)

• Transmission shift harsh/firm when warm
  • Problem: The transmission shifts harsh after driving for a while when tranny is warm.
    Solution: The PCS (pressure control solenoid) is acting up. You might have the code P1811. While the sensor is cheap, it is located inside the transmission and the side cover must be removed to access it. To remove the side cover, the subframe must be lowered to clear the frame rail. It is a very labor intensive fix.
    It has also been said that an aftermarket shift kit can help cure this problem.
    More info: https://tripleedgeperformance.com/harsh ... -dtc-p1811
    Estimated Cost: $40 for the new solenoid, but $400-1000 in labor.

I've installed the shift kit in dozens of these cars to eliminate the problem. Never had a come-back. $50 for the kit plus new fluid & filter and a couple hours in your driveway.

[polo]

You have a P1811 code.

From: 2000+ Common Problems & Solutions (updated 5.11.11)

• Transmission shift harsh/firm when warm
  • Problem: The transmission shifts harsh after driving for a while when tranny is warm.
    Solution: The PCS (pressure control solenoid) is acting up. You might have the code P1811. While the sensor is cheap, it is located inside the transmission and the side cover must be removed to access it. To remove the side cover, the subframe must be lowered to clear the frame rail. It is a very labor intensive fix.
    It has also been said that an aftermarket shift kit can help cure this problem.
    More info: https://tripleedgeperformance.com/harsh ... -dtc-p1811
    Estimated Cost: $40 for the new solenoid, but $400-1000 in labor.

I've installed the shift kit in dozens of these cars to eliminate the problem. Never had a come-back. $50 for the kit plus new fluid & filter and a couple hours in your driveway.

Thank you VERY much!

I noticed there are a few YouTube videos that show how to install it... one specifically for a 3800...

Is there a reason it just started literally after the dealer did the transmission flush (but didn't put in a new filter or seal as they stated they are good for a lifetime...)... ?

[harofreak00]

In my opinion, flushes are never a good idea. But probably just a coincidence.

[polo]

In my opinion, flushes are never a good idea. But probably just a coincidence.

Yeah... I know, I told them I wanted a drain and fill and not a flush - but they did a flush anyway...

[dougtoth]

I agree with Andrew.
My garage where I take my car threw out their machine.
He told me there were too many problems after the flush.
What happens sometimes is that it stirs up all the dirt and particles.
As a result the dirt and particles can block up the passages where the fluid
normally flows in the transmission.
The best way is to drop the pan and change the filter and add the 4 quarts of new fluid.
If you want to you can drop the pan and change the filter and add 4 more quarts of fluid again after a short period.
The reason some shops still flush is because it is fast and is a money maker.

[nos4blood70]

Installed my kit around 70k miles and now at 227k. Haven't had any hard shifting since.

It's a pretty easy job but can be a little messy.

[polo]

Installed my kit around 70k miles and now at 227k. Haven't had any hard shifting since.

It's a pretty easy job but can be a little messy.

So you have had no transmission problems at all - other than the hard shifting that this kit took care of...?

[craigstyz]

2025 THREAD UPDATE: Just got the PCS replaced on my car per the TSB you listed. Same condition. 30 min key on driving, hard shift. Re start and normal shifting resumes. Fault code P1811 stored. I had a trans shop do it for $800 labor, filter and new fluid. I paid $40 for an AC Delco PCS from Rock Auto. While the shift kits may or may not work, the PCS is the proper repair. P1811 is a code that affects so much performance issues that are erratic and intermittent. From hard upshifts hot, to lockup engagement overall shift point timing and quality. Mine truly runs like a bear now. It was worth the money I spent on it.