03 Impala Intermittent Hard Shifting with 1811 code

[lhrn]

Hello
I have this problem for last 6/8 months. My car (Impala 2003 3.4) shifts hard (feels like someone hit you from behind) intermittently (Once in every week if I drive hard). If I turn off the engine and let it sit for 2 mins, it runs fine. I took it to the dealer and they told me that they found code p1811 but they need to open the transmission to find out the problem. It will be a minimum 4 hr to 8 hr job. Local transmission stores want to sell a rebuild one.

Can it be the PCS (pressure control solenoid)? I know 2000-2002 models have this problem. Does 2003 has the same problem?

I would really appriciate any help.

[j cAT]

Originally Posted by lhrn

Hello
I have this problem for last 6/8 months. My car (Impala 2003 3.4) shifts hard (feels like someone hit you from behind) intermittently (Once in every week if I drive hard). If I turn off the engine and let it sit for 2 mins, it runs fine. I took it to the dealer and they told me that they found code p1811 but they need to open the transmission to find out the problem. It will be a minimum 4 hr to 8 hr job. Local transmission stores want to sell a rebuild one.

Can it be the PCS (pressure control solenoid)? I know 2000-2002 models have this problem. Does 2003 has the same problem?

I would really appriciate any help.

the transmission will require pressure testing and then it will be determined what needs to be repaired..... i also would not get another transmission but have the repair shop rebuild/repair your transmission....if they cannot repair your transmission then bring to a repair shop that has the knowledge to fix.your transmission .....these other shops are nothing but parts changers...



if the fluid is clear and not contaminated there is no reason to replace your transmission...

[BNaylor]

Welcome to AF.

How many miles do you have?

GM was supposed to revise the PCS solenoid in 2003 and up GM cars with the 4T65E autotransaxle but there are 2003 owners experiencing PCS problems regardless. The P1811 DTC (max adapt, long shift) is consistent with a bad PCS but as mentioned further diagnostics is required. The hard shifting is caused by the DTC setting and forcing the PCM module to command maximum line pressure and disabling shift adapts. Many owners had good luck with just the PCS replaced so that may be a good option. Cost will vary depending on where you live. $500 and up with the part (US only).

It is located under the side cover assembly with the valve body.


EPC=PCS

[impalalover]

Originally Posted by lhrn

Hello
I have this problem for last 6/8 months. My car (Impala 2003 3.4) shifts hard (feels like someone hit you from behind) intermittently (Once in every week if I drive hard). If I turn off the engine and let it sit for 2 mins, it runs fine. I took it to the dealer and they told me that they found code p1811 but they need to open the transmission to find out the problem. It will be a minimum 4 hr to 8 hr job. Local transmission stores want to sell a rebuild one.

Can it be the PCS (pressure control solenoid)? I know 2000-2002 models have this problem. Does 2003 has the same problem?

I would really appriciate any help.

yes it is your pcs,theses cars are famous for it,it is a 6-8 hour job and stores a hidden code of p1811 and shows exactly what the problem is,your pressure control solenoid,all it is is a valve

[lhrn]

Thanks for replying guys

115,000 KM

Did anyone have this problem? and how it got solved?

Originally Posted by BNaylor

Welcome to AF.

How many miles do you have?

GM was supposed to revise the PCS solenoid in 2003 and up GM cars with the 4T65E autotransaxle but there are 2003 owners experiencing PCS problems regardless. The P1811 DTC (max adapt, long shift) is consistent with a bad PCS but as mentioned further diagnostics is required. The hard shifting is caused by the DTC setting and forcing the PCM module to command maximum line pressure and disabling shift adapts. Many owners had good luck with just the PCS replaced so that may be a good option. Cost will vary depending on where you live. $500 and up with the part (US only).

It is located under the side cover assembly with the valve body.


EPC=PCS

[jenndelapp]

I have an 01 Impala with this same issue P1811 code stored. 112,000 hwy miles, always been babied. Mine acts up when the engine temp gets to one peg under half or above, but never goes above half. It acts up the most shifting from 2nd to 3rd.

I took it to the local trans place and they said that just changing the PCS tsb 0O-07-30-002B doesn't usually fix the problem. They recommend following the new 2008 TSB 08-07-30-002 for reconditioning all the valves. None of the known codes listed in this bulletin show up in my computer. So I am wondering if they are just trying to take me for the extra money.

I have recently had the transmission flushed and the filter replaced. We add Sea Foam to the new fluid and its shifting a lot better, only a minor harsh shift now. The reason we did this is another trans shop told us that if the codes mentioned in tsb 08-07-30-002 are being stored, your trans is already on the way out the door so you will be sticking $750 into something you are going to have to replace anyway in the near future.

The first trans place is telling me if I don't have the valves reconditioned and just the PCS done, that I am going to ruin my transmission even if it feels like it is shifting ok. Bill will be $750, which of course I don't have.

Can anyone shed any light on whether they have done just the PCS and not had to have the valves reconditioned? Did you continue to have problems?

Also any thoughts on whether the first trans shop is feeding me a line or if there is some truth behind it? Since it is doing it between the same two gears and not through out the whole shift pattern, should I be looking at replacing the clutch assemblies and not the PCS or value reconditioning?

Thanks!!

[BNaylor]

Hard to say on whether the transmission shop is off base because there are too many variables involved. It is somewhat true that people that have the PCS replaced may see it act up in the future. Worn out clutch pack is possible. The reason why the P1811 DTC sets is the PCM sees shift timing greater than .65 secs. When P1811 (max adapt, long shift) sets it commands maximum line pressure and disables shift adapts therefore you get the hard/harsh upshifts and possibly a whining sound. Checkout the thread below which may help out and possibly save you some money plus allow you to get some more mileage out of the autotransaxle. So far the fix has worked for many AF members.


Click here

[wafrederick]

The aftermarket sell the updates,two solenoids.I cannot remember the name of the aftermarket company that sells the update

[BNaylor]

The 2003 and up Impalas with the 4T65E, GM RPO code M15 autotransaxle already have the so called revised/improved pressure control solenoid.

[HeMi101]

Some of the earlier 03's didn't get them though, They were built before they started using the new one.

[BNaylor]

Originally Posted by HeMi101

Some of the earlier 03's didn't get them though, They were built before they started using the new one.

Yeah I guess thats possible. Regardless, really doesn't make any difference. The revised/improved PCS is not backwards compatible. It can only be used with the '03 and up Impalas that had them from the factory. So some 2003 and '00-'02 owners are S.O.L. on that issue. The change included valve body modifications.

[monteheeren]

My 2002 Impala LS had exactly the same problem. I replace the pressure control solenoid and now the car shifts like a million bucks! I serviced the trans while I was there. Getting the trans side cover off was a pain in the butt. I pulled the frame and serviced the steering intermediate shaft while I was there. Heard the intermediate shaft will develop a clunking sound later if not lubricated correctly. Was ready to sell the darn car, but now that it runs so good, I gave it a bath and decided to keep her!

This forum is priceless!

[c581074]

i had this same problem with my 2003 impala same code and averything from what i understand the trani is just wore out now the trani adjusts to ware to keep it shifting right but when it gets to worn out it can't adjust anymore so u will just need a new or rebuilt one it is not any switch located on trani or anything else it's just worn out too much

[manteca]

I have 2003 also with same problem. Took to trans man, he hooked up electronic code reader and device showed 1811. He asked me if I wanted him to erase code and it may eliminate problem. I said yes and he hit erase and the problem has gone away. It took 5 minutes and he didn't charge me. He said if I took to dealer they could update software to solve problem if it persists.

[HeMi101]

Originally Posted by manteca

I have 2003 also with same problem. Took to trans man, he hooked up electronic code reader and device showed 1811. He asked me if I wanted him to erase code and it may eliminate problem. I said yes and he hit erase and the problem has gone away. It took 5 minutes and he didn't charge me. He said if I took to dealer they could update software to solve problem if it persists.

Oh Just be patient, It'll Come back. IT WILL. Just might take time, or could happen tomorrow.

Mine came back, so I haven't bothered to clear it again. I just ignore it, as the Harsh shifts don't bother me, and she'll hold out long enough. I just keep an eye on the fluid Condition.