Hello yall! I have a 2013 Corolla 120k miles auto transmission. Ill be going about 65-70 mph on cruise control the car will downshift to gain speed then on the up shift the transmission thuds real bad. It’s only done it recently(past 1-2 months) maybe 3-4 times. It seems to only do it when the car is cold, doesn’t do it when car is warm. I don’t know anything about transmissions. Is this a sign the tranny is going bad? Thanks for any help
P.S I check the tranny fluid level and its fairly new and at proper level.
The transmission fluid is still nice and pinkish red
Good that the fluid is not dirty or gritty. What about the filter? That may have not been changed and could be clogging up if original.
A quick check of recalls and TSBs doesn't turn up anything for the transmission on that car. I did find this, which sounds similar to what you are experiencing:
Serious transmission problems look to be rare on that model unless it's been abused. However, solenoid and sensor problems are fairly common on electronically-controlled automatic transmissions. You would need a transmission expert to diagnose that using a fancy scan tool.
You could also check to see if the car's transmission control software is up to date. (You need to check with a Toyota stealership on that one. Or, if you have a Carfax or similar report, see if software updates have been reported.)
If do you go to a stealership to check for software updates don't let them sell you a new transmission or other upsells. Walk out if they do that and get another opinion from a good local transmission shop. Dealerships are motivated to replace parts rather than spend time diagnosing a problem, and service writers are commissioned sales people.
@chucktobias good stuff. Thanks for the reply. Your comments are always solid
When is the last time the transmission fluid was changed?
@chucktobias good question. I bought it at 108k miles. I haven’t done it. . I should specify by fairly new. The transmission fluid is still nice and pinkish red
trans fluid changes viscosity (resistance to flow) with temperature, and the shifting is hydraulically activated, so not too unusual if it's cold. It could also be a sign the trans is starting to wear out in the valve body. I would drain and fill the fluid for peace of mind, regardless of how it looked. Then do it every 50k.
