Transmission starting to act up a bit

[kristie_jeff]

Today I started noticing my car was shifting a lot harder than normal. I left work and it was fine. About half way home (apr. 7 mile total trip 1 way) it started shifting hard from 1-2 and 2-3.

While I was waiting on my kid to get out of school (about 25 minutes with the car off) I read several posts on here about the PSC, but I wonder if it might be something else. On the way to the house from school, it still did the same, maybe a little lighter on the shifts, but definitely not as smooth as usual.

Ambient temp right now is about 65-70. I checked the fluid when I got home, engine running, and the level is right up to the top of the hashed area of the stick. Color is about medium pink. I did notice that there are a lot of tiny little bubbles on the stick. I checked it 3 times to see if the bubbles were still there.

Any suggestions? Will the scanner things that Autozone has pull codes for the transmission?

*Edit:
Wanted to add that when this happens, there's not noticeable "hang time" in between gears. The rpms don't go up or anything that I can hear or see on the gauge. Also, this is the 4T65-E (M15 code) if that helps

[Ken_W]

What is the mileage on this car?

Ken_W

[kristie_jeff]

Sorry, I guess that would help a bit. 66,727 as it sits in my garage right now. I'll also add that I purchased it at around 28,000, and at least since I've had it, the trans fluid/filter has not been changed or flushed.

[1fatcat]

Faulty PCS is a very good possibility. It can be tested, but a tech2 scan tool and fluid pressure guage are needed.

[LeSabre in Buffalo]

Smells like another PCS, even though yours is an 05 with the revised parts.

Try pumping out the pan and refilling with new ATF. It could just need some new ATF. Valvoline Maxlife ATF, my choice for the 4T65, is $3.67 a quart at Wal-Mart. You'll need about 6 quarts to refill the pan. And one of those $8 hand pumps they sell to pump out the pan. With tax, it should run about $32 for 6 quarts of Maxlife ATF and the pump.

[yonkerse]

Hey man,

I have experienced this exact hard shift from my 2005 SLE with 85,000 miles. I have had it happen to me twice over the last 10,000 miles on the car and when scanned, its displayed the P1811 code. Im sure this is the issue within your car like others have suggested. If your car is still under warranty, I would take it to the dealer and let them take care of it.

I have 1000 miles left on my warranty and im really trying to get the code to display again to let them fix it.

[enslow]

Smells like another PCS, even though yours is an 05 with the revised parts.

Try pumping out the pan and refilling with new ATF. It could just need some new ATF. Valvoline Maxlife ATF, my choice for the 4T65, is $3.67 a quart at Wal-Mart. You'll need about 6 quarts to refill the pan. And one of those $8 hand pumps they sell to pump out the pan. With tax, it should run about $32 for 6 quarts of Maxlife ATF and the pump.

You installed that partial transgo shift kit didn't you?

I've read elsewhere that what you did by changing the fluid, doing the shift kit in the valve body, and changing the filter solves most PCS issues. While it doesn't correct the PCS problem directly, it seems to prevent or reduce the situation where the PCS causes trouble. From what I've heard, some people can go years after without having to do expensive transmission work.

[ironoxide]

You're not alone. It really does sound like the car is going into adaptive shift mode (P1811). My suggestion is to bring it to the stealer and have it diagnosed - I'm betting good money you need a new PCS. I would not recommend trying to solve this problem by changing out thermostats or putting in trans kits. The dealer should be able to read the code no problem with their scan tool, and test drive it to check for low voltage.

[Archon]

The harsh shifts are often caused by defective pressure control solenoid. When the PCM detects that it is taking too long for the transmission to shift, it puts it into a protection mode by commanding maximum line pressure and setting code P1811. (That code will not show up with most standard code reader.) That is what causes the harsh shifts. It is not caused directly by the PCS.

Much will depend on how much you want to spend. You can take it to the dealer, or a transmission shop and pay maybe $600 or so to have it diagnosed and the PCS replaced. Or, you can install the shift kit for around $100 and solve the problem that way. This has been a successful solution for many. This is a good article regarding that code.
http://www.tripleedgeperformance.com/Ha ... P1811.html