03 Impala Intermittent Hard Shifting with 1811 code

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.

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...

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.

http://i5.photobucket.com/albums/y186/lizzywiz/valvebody2.jpg
EPC=PCS

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

Thanks for replying guys

115,000 KM

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

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.

http://i5.photobucket.com/albums/y186/lizzywiz/valvebody2.jpg
EPC=PCS

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!!

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 (http://www.automotiveforums.com/vbulletin/showthread.php?t=899929)

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

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

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

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.

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!

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

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.

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. :banghead::lol: 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.

yes i just got mine changed... i have a 03 impala...

My 03 had a diagnostic test and came up with code p1811. Felt slight slip when driving and excellerating. Not major just annoying, was like pressing the gas and letting up and pushing again. Does not happen very often .Mechanic recomended transmission flush. Suggested that this would fix the problem. Is that possible?

the best and cheapest thing to do is call GM and complain. Their number is 1-800-222-1020. These transmissions are known to be defective but have yet to be recalled. I called today 6-21-2010.

Faulty Pressure Control Solenoid, GM knows about it, there are TSB about it. Harsh shifts when hot. The best and cheapest thing to do is call GM and complain. Their number is 1-800-222-1020. These transmissions are known to be defective but have yet to be recalled. I called today 6-21-2010. Ask for it to be recalled. If they get enough calls they will. Maybe

UPDATE
GM was useless, I ended up getting transgo sk4t65e kit and using the accumulator springs and spacers, shifts great, cost about 160 and really easy to do

I was dreading changing the pcs, but it was easier than i thought. I am not a mechanic and I am not suggesting that you do this, this is what I did and it worked fine and saved a bunch of money and was easy to do. Anything you decide to do is your choice and I am not liable for it
1. disconnect battery and drain transmission fluid, put transmission pan back on with a few bolts, you can change the filter when you are done with everything else and put all the bolts back in
2. take off air filter housing and air intake, take electrical plug out of transmission
3. raise boot on steering gear box and take bolt out of steering connecting to steering shaft, it is one bolt and has to come completely out and then slide the shaft up off of it (this is done so you do not damage the steering when you lower the cradle)
4. loosen axle nut and lug nuts so you can get them off when you raise the vehicle.
5. raise vehicle,and support it,take off the following only on drivers side: wheel, brake caliper (hang out of way), lower ball joint off of lower A arm, tie rod end, sway bar
6. now you can take out the 3 strut nuts from up top and tap on the axle nut very lightly, then take the axle nut off to get it out of the front hub assembly,
7. push down on the lower A arm, and pull the strut out (i left the strut, rotor, front hub assembly as one when i took it out), also take out engine splash shield which has 3 plastic rivets in it, then pull out axle, i used a slide hammer
8. I had 3 different areas of support , the body, the transmission, and the front drivers side cradle
9. I placed a piece of plywood on the jack and used it to support the transmission, be careful not to raise it to high and crack your coolant reservoir
10. I placed another jack on the cradle
11. I used jack stands to support the body
12. I took out the tranny mount nuts that bolt it to the cradle.
13. With the tranny supported, as well as the Cradle, I loosened the 2 drivers side cradle bolts and took them completely out. Lower the cradle down. This allows you to get to the bottom bolts of the side cover. Then lower the transmission down to get the rest of the bolts out.
14. Pull off side cover and replace solenoids. Disconnect wire harness, they have a pin that you must pull out with needle nose pliers, pull out solenoid
15. Reverse procedure to assemble
16. got alignment

This job took about 5 hours, because it was my first time doing it, but it is real easy
I bought a solenoid kit off ebay for $108, fluid and filter for about $60, I used about 10 qts

every car is different so use common sense when you are working on it, you have no one to blame but yourself if you screw up, good luck

thanks for your results with this common Issue regarding GM' s defective transmission . anything over 7yrs and 100,ooomi its all yours. maybe seat belts they will rework if your lucky. yes GM on many common warrantee issues is useless if it takes more than 15min to fix.most other failures will require NHTSA to force action to fix defects if enough people get killed.


for not being a mechanic that is quite impressive work you did !

thanks for your input.

Try cleaning your MAF sensor, May help, the trans uses the MAXIMUM AIR FLOW sensor to determin what it needs to do. Use sensor safe cleaners, do not use the old style carb cleaner, you may need to dissasemble the MAF if it is the type that is in the middle of the airduct, will need a torx bit, squirt then swab with a q-tip. It won't hurt, they need cleaning regularly, especially if you have a K & N air filter.

chevymandan (http://www.automotiveforums.com/vbulletin/member.php?u=656413) wow that is a great way to do that, might I make one suggestion, bungee cord the steering wheel, when you disconnect the the intermediate shaft the steering wheel can turn...if it turns too much it will damage the air bag connectors. There is also a space at about 7:00 that you can insert a tool to lock the wheel.

Try cleaning your MAF sensor, May help, the trans uses the MAXIMUM AIR FLOW sensor to determin what it needs to do. Use sensor safe cleaners, do not use the old style carb cleaner, you may need to dissasemble the MAF if it is the type that is in the middle of the airduct, will need a torx bit, squirt then swab with a q-tip. It won't hurt, they need cleaning regularly, especially if you have a K & N air filter.

cleaning the MAF should be done with MAF CLEANER. following the instructions with these products , it clearly states, NOT TO TOUCH THE SMALL SENSING WIRES.

It is simply spray these wires with a one second spray. let dry , then install.. keep the runoff of cleaner from the electrical components is recommended.

touching these wires can cause damage to them. Q tip fluff can get on them . this would be very bad.

I'm having the same code and hard shifts when hot on my 02 Monte Carlo ss. I recently did a quick fix on a split in the side of my resonator until it gets warmer and I can replace it and it fixed the hard shifting issue. it wasn't until a few weeks ago when my quick fix failed it started shifting hard again

Resonator has nothing to do with P1811......