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    Jerking Transmission at Cruise Speed

    Hey guys, I've been having an intermittent issue with the transmission doing this odd jerking/slipping thing when I either drive over large bumps, encounter a hill, or just engage TC lockup sometimes.

    It feels like the torque converter might be losing grip when in lockup mode, which would cause it to slip and jerk, but I remember one time I shifted to third manually and it continued, so I thought I could rule that out. My '96 has about 135k on it right now. Anyone encounter this before?

    #2
    I had a similar issue on a 6000 with a 2.8 4 speed. It was just low on tranny oil. Going over bumps, or transitions, would create a sloshing effect in the tranny, and the pump would suck air.
    Brian - Carpe Diem

    I dont have to love my president, or any god, to love my country!!
    More people have died in the name of "God" than in all wars combined thruout history
    01 Pontiac Aztek GT AWD 127k - 04 GMC Envoy SLT XUV 193k

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      #3
      My 92 Trans Sport with 4T60E would do something like that. Sometimes the torque converter would shudder on engagement, other times it would disengage and throw a code. I checked the solenoids via the connector and they seemed weak so I bought new ones. All day job to get in there, solenoids were fine but the harness connections were loose. So I tightened them up and of course replaced solenoids anyway. Took care of the problem for awhile.

      So anyway with any luck maybe your outside trans connector is loose. I would clean and see if you can tighten the prongs.

      Another thing that happened was I lost half the shift solenoids. Plus a bunch of other stuff in the van. Got a quad driver code. Turned out to be a bad ignition switch, tons of stuff even higher powered accessories passes through that switch. Yet it?s the exact same switch since the 60s or 70s when cars were pretty barebones.

      Fluid and filter change (not a flush) can?t hurt either if it?s not been done for a long time.
      1989 Celebrity CL 4 door, 3.1 MPFI, 4 speed auto, summer daily driver
      1989 Cutlass Cruiser wagon, 3.1 MPFI, 4 speed auto, special summer ride
      1996 Cherokee XJ 4 door, 4.0, 5 speed, winter daily driver & towing vehicle
      1991 Tracker 2 door, 1.6, 5 speed, needs work
      Previously several Celebritys, 6000s, & 2 U-vans

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        #4
        Wow thanks for the input guys.

        Can you tell me where the outside harness is located? I changed the fluid in summer 2019 replacing with Dex VI, and I changed the filter too. Messyyyy!!!

        I've been keeping an eye on the fluid and keeping it full. I'm terribly afraid to overfill tho.

        I've had the car for 6 years now and don't wanna get rid of it. Runs and drives great still with 135k miles.

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          #5
          The connector should be on the front of the transmission, near the top.

          The harness is inside the transmission side pan. A lot of work to remove. Hopefully the outside connector offers some improvement.
          1989 Celebrity CL 4 door, 3.1 MPFI, 4 speed auto, summer daily driver
          1989 Cutlass Cruiser wagon, 3.1 MPFI, 4 speed auto, special summer ride
          1996 Cherokee XJ 4 door, 4.0, 5 speed, winter daily driver & towing vehicle
          1991 Tracker 2 door, 1.6, 5 speed, needs work
          Previously several Celebritys, 6000s, & 2 U-vans

          Comment


            #6
            Well it doesn't appear to have done anything. It still happens intermittently. Do you think that it would pose a danger to let it continue as is? I'm not sure I can do what you did.

            Also you said it helped but for only some time?

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              #7
              Does it happen while you are using cruise control?
              Brian - Carpe Diem

              I dont have to love my president, or any god, to love my country!!
              More people have died in the name of "God" than in all wars combined thruout history
              01 Pontiac Aztek GT AWD 127k - 04 GMC Envoy SLT XUV 193k

              Comment


                #8
                Originally posted by Pontiac6ksteawd View Post
                Does it happen while you are using cruise control?
                CC doesn't work anymore :/ It's very intermittent and won't occur for long.

                Comment


                  #9
                  Sounds like you need to check all the vacuum lines then. Starting with the cruise control, working your way from there.
                  Brian - Carpe Diem

                  I dont have to love my president, or any god, to love my country!!
                  More people have died in the name of "God" than in all wars combined thruout history
                  01 Pontiac Aztek GT AWD 127k - 04 GMC Envoy SLT XUV 193k

                  Comment


                    #10
                    That?s what my van did too. Every time the trans would break connection, cruise control would drop out.
                    1989 Celebrity CL 4 door, 3.1 MPFI, 4 speed auto, summer daily driver
                    1989 Cutlass Cruiser wagon, 3.1 MPFI, 4 speed auto, special summer ride
                    1996 Cherokee XJ 4 door, 4.0, 5 speed, winter daily driver & towing vehicle
                    1991 Tracker 2 door, 1.6, 5 speed, needs work
                    Previously several Celebritys, 6000s, & 2 U-vans

                    Comment


                      #11
                      Still good to check for vacuum leaks, but the '96 cruise control is completely electronic. Much better than the vacuum servo units, IMHO.
                      Jerry

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                        #12
                        My book shows the Century didnt get electronic cruise until 97.. So I am not sure on that one. Would have to see his CC servo.
                        Brian - Carpe Diem

                        I dont have to love my president, or any god, to love my country!!
                        More people have died in the name of "God" than in all wars combined thruout history
                        01 Pontiac Aztek GT AWD 127k - 04 GMC Envoy SLT XUV 193k

                        Comment


                          #13
                          Our late '96 positively has it, if there is some odd, non-model year break.
                          Jerry

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                            #14
                            I know I have seen others before too. Looked it up but they appear obsolete now, like most everything with cars so old from a bankrupt company.



                            You can get the cruise control servo rebuilt through '93 on Rock Auto by Cardone. Nothing listed '94-'96. Picks up again with '97.
                            Jerry

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