My automatic 2000 Bonneville is shifting hard when it switches gears. The car fetches when it shifts - but it doesn't stall.

It shifts in and out erratically. Going up a hill it'* in overdrive.

I hooked it up to a diagnostic tool that said the torque converter clutch is engaged.

Does anyone know how I can fix this?

Where is the torque converter clutch located?

Thanks!

Indeed, the torque converter being locked up would cause shifts to be hard like that, but I'm curious as to why it stays locked up all the time, but you can still start the car out in from a stopped position.

Only thing I can think of that would cause that would be the solenoid is sticking open/closed to enable the lockup feature of the TCC.

Do you remember what the code was?

Thanks for your quick reply Mike.

It says the torque converter clutch is engaged but the car still starts fine and doesn't stall - only shifts hard when it'* going. A friend used his diagnostic tool - I don't have the code with me but he wrote it all down. I can call him later and get it. I have a handheld diag tool I can try.

Could it be a dirty filter/low fluid pressure do you think?

Changing the filter, fluid and installing a low cost shift kit have all been methods for a long term bandaid on many of the shift problems you are experiencing. I had the same problem you are describing at 90k miles. I installed the shift kit, replaced the filter and upgraded the fluid to DEXRON XI. I am now at 182k miles and tranny still working good.

Hi Michael,

Thanks for your reply. That'* great - I have a whole case of Dexron. I'm going to get a filter now and try what you suggested. I'll let you know how it goes.