I have a 2001 pontiac grand prix with 121k miles, today I got a P1811 code, time to time I get hard shifts for 1-2. I drive 10 miles a day for my teaching job. I checked the selonids using the scanner, it is working through the gears as it should be. I changed my transmission fluid with valvoline dexron 3, 3000 miles ago with new filter, the fluid level is OK, and color is good. Is it true that when you change your fluid, it is common to have hard shifts and does it go away once the fluid gets older say after 10k or 20k miles? Is it okay to drive the car for another 1000 miles? What are my options? Put new selonids or full transmission rebuild? The car may worth $500 but it is worth a lot more to me, I have this car for the past 13 years. I drive 2000 miles a year. Any suggestions or opinions are welcome.
P1811 code on my 4t65e transmission, what are my options?
- Thread starter easym
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There is also a shift kit that sort of works around these problems, it installs in the valve body and would only be a few hundred bucks. Though I thought the 2-3 shift was the "hard" one this kit typically fixes.
You can and should also try a bottle of Lubegard Red. Hard shifts are better than sloppy shifts, until they reach a point when all the banging starts breaking things.
You can and should also try a bottle of Lubegard Red. Hard shifts are better than sloppy shifts, until they reach a point when all the banging starts breaking things.
Was it doing that before you changed the fluid? 
Reset the CEL and see if the code comes back or any other problems.
Reset the CEL and see if the code comes back or any other problems.
ls1mike
$50 Site Donor 2024
TransGo Shift kit. Try it. If you changed the fluid you can do it yourself. The kit is like 50 bucks.
transgo.com
4T65E SHIFT KIT® Valve Body Repair Kit
The TransGo 4T65E SHIFT KIT® Valve Body Repair Kit is the perfect solution to shorten the shifts without making them rough.
This
Read up here as to the causes and comments about the kit. https://tripleedgeperformance.com/harsh-shifts,-dtc-p1811
This is the way to go, especially since it's not too difficult and reasonably inexpensive. I had an old Buick that developed a hard 1-2 shift and the kit solved it. When I say hard, it was a hard bang! I didn't need to use all the parts either, there was one component in the kit that was much more involved that I didn't install. As I recall I only needed to install some springs and spacers.TransGo Shift kit. Try it. If you changed the fluid you can do it yourself. The kit is like 50 bucks.
4T65E SHIFT KIT® Valve Body Repair Kit
The TransGo 4T65E SHIFT KIT® Valve Body Repair Kit is the perfect solution to shorten the shifts without making them rough.
Read up here as to the causes and comments about the kit. https://tripleedgeperformance.com/harsh-shifts,-dtc-p1811
On GM, P1811 means "Maximum Adaptive and Long-Term Shift Times"
In other words, the computer thinks it's shifting too slow.
The max line pressure will eventually break something, The trick is.....Don't keep driving it in this condition. The TransGo shift kit shortens shift times via limiting Accumulator range.
Do you think if I manually put my gear in 3rd and keep my driving below 40 mph ( I only use the car for city driving), I can stop hard shifts and buy more time?
If it was the 3-4 shift causing the issue...Sure. But I highly doubt that's the case as it's usually the 1-2 or the 2-3.
The TransGo kit is the least expensive option.
I could tune the issue out with tuning software by adding some extra pressure where it's needed to shorten shift time & turn P1811 off.
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Yes! I have 2 words for you! Yes, Shift Kit!
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Not Most Likely Toast.
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The hard shifts are due to the line pressure being maxed out,
True, But It will return to normal pressure after a key cycle.
Keep seeing slow, long shifts, pressure back up!
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Please, lets not condemn the tranny before its time.
From personal experience, the shift kit with the updated accumulator springs does work, at least in some cases. When the computer sees shift times taking longer than .65 seconds for too many times, it will set the line pressure to maximum to keep the clutches from getting burned up and sets the P1811 code. The maximum line pressure setting causes the "bang shifting." This is also why it may take a while to happen when you start driving it when the car is cold. In my case. installing the accumulator portion of the TransGo kit reduced the shift times to less than .30 seconds when hot.
Another issue that can cause problems is the pressure control solenoid, but this is not easy to reach as you need to access the valve body which requires pulling apart the driver's side suspension and dropping the sub frame member down to gain access.
Another issue that can cause problems is the pressure control solenoid, but this is not easy to reach as you need to access the valve body which requires pulling apart the driver's side suspension and dropping the sub frame member down to gain access.
Is rebuilding a transmission worth on a 20 year old car like mine?
Lots of good advice to try first before an expensive rebuild. Lubeguard --> shift kit --> buys you time on an old vehicle.