Hard Downshift

[gnonne]

When braking from 45 mph to a stop, I get a hard downshift at 29-32 mph every time. Hot or cold engine does not matter. 2012 1.8L with 6 speed auto, 38k miles. I have three Sonics and the other two don't do this - never have.

Seems to have started now that the weather has turned colder in MI. I think it did this last winter and they re-programmed it, but I don't think it ever really fixed it.

I suspect something internal, as it does the same thing when downshifting in manual mode, but ONLY on the downshift from 5th to 4th gear.

Ideas? Thanks

 

[gnonne]

How do you add trans fluid?

When the car is fully warmed up (which does not happen on most of my short trips) the problem goes away completely.

Thinking the fluid is just a bit low, then once the fluid warms and it expands, its OK. (Hydraulic oil expands quite bit to my knowledge.)

How does one add fluid? Owners manual says to take it to the dealer.

 

[Maddmatts]

Automatic transmissions moved from 'user serviceable' to 'sealed for life' a decade or so ago. It can be done at home if you know what you're doing.

I'm not sure where everything is on the 6T30 that's used with the 1.8L but I'll assume it's similar to the 6T40 used with the 1.4.

Your car will have to be parked somewhere reasonably level. The fill port will be on the top of the transmission on the driver-side of the engine bay and will probably be between the engine and the battery/ECM tray. You'll likely need a long, narrow funnel to reach it. You will also need to locate the level port on the bottom or side of the transmission which will be blocked off with a bolt or plug. Unblock it. Pour fluid in until it dribbles out the level port. It's now considered full.

 

[danmiller]

I have exactly the same problem. The dealership replaced all fluids and put the laptop on there to do some type of update. It helped but did not correct the problem, and now a few months later the problem has fully returned. I see your post was a few years ago. Were you able to get it fixed? If so, what did you do? Thanks.

When braking from 45 mph to a stop, I get a hard downshift at 29-32 mph every time. Hot or cold engine does not matter. 2012 1.8L with 6 speed auto, 38k miles. I have three Sonics and the other two don't do this - never have.

Seems to have started now that the weather has turned colder in MI. I think it did this last winter and they re-programmed it, but I don't think it ever really fixed it.

I suspect something internal, as it does the same thing when downshifting in manual mode, but ONLY on the downshift from 5th to 4th gear.

Ideas? Thanks