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Bob
Bob, Auto Tech
Category: Chevy
Satisfied Customers: 4087
Experience:  Plus 40 years GM, over 30 certified with Chevrolet, ASE certified Master Tech. (Expired, Retired)
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2000 LS: day 100 miles..freeway..transmission shifts..occasionally

Resolved Question:

Hello, I drive a 2000 LS impala with the 3.8 litre engine. 192 k on it today and I know its alot of miles but I do keep up with ALL of the maitenance and it gets me to work every day 100 miles round trip, all freeway miles. The transmission shifts hard occasionally and more so lately. I''ve noticed that if I stop the car and turn the engine off, then restart it, the hard shifting goes away. Is there some kind of sensor that may be causing this? I know that the fluid and filter were recently changed within the last 5 k miles. Any ideas for me to try?
Thanks,
Pete
Submitted: 6 years ago via CarComplaints.com.
Category: Chevy
Expert:  Bob replied 6 years ago.

Hello, sometimes shutting the motor off and restarting it will make the computer reset everything and anything that may have a glitch in it. There have also been some problems with AC actuators that this will cause to clear up temporarily. The only thing I can come up with that could cause your problem is the Pressure Control Solenoid Valve. This is a component that can cause many different types of trans problems. It has been so prevalent that GM has issued a technical bulletin for the technicians, so they would be aware of it. Replacement requires removal of the trans oil pan. This valve controls the trans line pressure of the fluid and that causes problems when it is not correct. Too much makes harsh shifts, to little let them slip into gear or too soft a shift. The correct way to test it is with a hand held class 2 scan tool like the Tech 2 that the GM dealers use and a line pressure gage. This tool will read the codes, which the valve may or may not set. If it does the service soon light will come on. But the nice thing is that with the scan tool the technician can run function tests on the components inside the trans to see if they are functioning correctly or not. Testing usually costs about an hours labor. Below is some info on the valve from the service manual. I wish I could post the bulletin for you, but the file is so large that the site won't accept it for posting, But the GM technical bulletin number is XXXXX Thanks

Subject:Slips, Harsh Upshift or Garage Shifts, Launch Shudders, Flares, Erratic Shifts and Intermittent Concerns, DTC P1811 or P0748 Set (Replace Pressure Control Solenoid Valve Assembly)

Models:1997-1999 Buick Riviera
1997-2002 Buick Park Avenue
1998-2002 Buick LeSabre
1999-2002 Buick Regal
2000-2002 Buick Century
2002 Buick Rendezvous
1997-2001 Chevrolet Lumina
1997-2002 Chevrolet Monte Carlo
1999-2002 Chevrolet Venture
2000-2002 Chevrolet Impala
1997- 1999 Oldsmobile Eighty Eight
1997-2002 Oldsmobile Silhouette
1998-2002 Oldsmobile Intrigue
2001-2002 Oldsmobile Aurora (3.5L)
1997-2002 Pontiac Bonneville, Grand Prix
1999-2002 Pontiac Transport/Montana
2001-2002 Pontiac Aztek
with Hydra-Matic 4T65-E (RPOs MN3, MN7, M15, M76)

  • Access the PC solenoid valve control test on the Scan Tool.
  • Increase the PC solenoid actual current from 0.0 to 1.0 amps in 0.1 amp increments. Allow the pressure to stabilize for five seconds after each pressure change. Read the corresponding line pressure on the J 21867.
  • Refer to the Line Pressure specification table. Compare the data to the table.
  • If pressure readings differ greatly from the table, refer to Incorrect Line Pressure.
  • Remove the J 21867.
  • Apply sealant, P/N 12345382 (in Canada, P/N 10953489), to the oil pressure test hole plug.
  • Pressure Control Solenoid


    Object Number: 49378  Size: SH

    Parts Information

    Part Number

    Description

    10478146

    Pressure Control Solenoid - Valve Asm.



    Customer: replied 6 years ago.
    Bob, thanks for gettting back with me on this issue. I understand most of your answer with a question about the service engine light you mentioned. It has not come on due to this problem. Do I get a tech to check that first or do I go to a transmission shop with this?
    Expert:  Bob replied 6 years ago.
    The light will not always come on, that's the bad part. But if it does, it makes it that much easier to diagnose the problem. They need to use the same tool to check it for codes as they do to function test the electronic components in the trans. So, it really doesn't matter which way you go. If they are any good, they will check it for codes automatically. There is also a history code stored in the computer, so if the code ever showed up, it will still be in there even if the light is off. Unless some one has cleared it with the tester or the battery has been unhooked in the car. I personally think you would be better off dealing with a GM dealer on this kind of an issue, only because they know all of the little idiosyncrasy's of this transmission better than anyone. And not all transmission shops have the class 2 scanner. A good scanner will cost in the area of 3 to 4 thousand dollars, but for GM dealers it is a required tool and furnished to them by GM. Just my own personal preference. If you have a good trans shop that you trust and they are certified and offer a guarantee on their work like the dealer does, then by all means. What ever you are comfortable with. Just be sure you ask about a warranty no matter who does the work and get a written estimate first so you know where you are with it. If I can assist in any other way, just drop a note. If I am not on line at the time, the system will notify me when I do sign on. Thanks
    Bob, Auto Tech
    Category: Chevy
    Satisfied Customers: 4087
    Experience: Plus 40 years GM, over 30 certified with Chevrolet, ASE certified Master Tech. (Expired, Retired)
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