O.K., I'm pretty new to this site. I recenlty bought a toy - a 2001 Bonneville SSEi.
It has a sort of "gradual shift" at times between first and second. Sometimes - but not always. On occasion, it has a real hard shift from 2-3, 3-4. When this hard shift business starts, I have two choices. I can put the car in neutral, shut it off and immediately crank it up and put it back in gear and it'* fine. If I don't do this, eventually the SES light comes on and my mechanic says it'* a transmission code.
The only time I ever get a Service Engine Soon light is when the transmission is acting up. If I shut it off and re-start it, it works great. I'd say that this hard shift problem happens maybe once a week. I drive 30 miles each way for work every day. I'd say once a week, I'll have the problem either in the morning or the afternoon. When it happens, it is only after driving about 15 minutes.
I grew up doing everything on all of my cars, but now I'm 48 and a little less adventurous. Right now, a transmission rebuild is not in the budget. I've been told that changing the fluid may make the problem worse. I'm tired of pampering this car due to fear of the transmission locking up or going out all together.
Any words of wisdom?

First thing I would like you to do is go threw this trouble shooting guide and see if any of it fits.

https://www.gmforum.com/t279318/

How many miles do you have on this car? Do you know off hand what the SES code was? Changing the fluid is a good first place to start. Unless the transmission is really shot, changing the fluid and filter shouldn't hurt it. If your concerned I suggest not doing a flush, just filter and fluid. Here'* a write up on how to do that.

https://www.gmforum.com/t278813/

When you check your fluid, how does it look? Is it nice and red, or darker brown?

The car has 135,000 miles on it. One week after I purchased it, the motor spun a bearing. I got it cheap, so I bit the bullet and installed a new GM crate motor. One week later, the transmission started acting up. The fluid is full. It'* not new fluid, but it'* not brown and it doesn't stink like burned fluid does.
The real "head-scratcher" for me is that it is not consistent. It'* one of those "sometimes" problems. Also the fact that if the thing is acting up, I can shut it off, then immediately re-start it and it'* fine.
Thanks for your response.
The SES light is on right now, so I'll go somewhere and get the exact code. Would that help any?
I'm hoping for a replaceable bolt on part and not a overhaul.
Thanks again,

Right now I would lean towards the filter being plugged up. It would explain what you are seeing. Loss of pressure can cause a slow shift. If you open it up and change the filter I suggest pulling the shift modulator and checking the Orings. This is easy to do. This write up is about installing a shift kit, but it'* no different to take it apart and inspect it.

https://www.gmforum.com/t278802/

Dan, you are the man.
I can't help but comment though. I'm assuming it'* you in the pictures. You strongly state that it is important to use GM transmission fluid, but I couldn't help but notice that you're using the same brand that I use. Is that not a Wal-Mart brand I see you using?
I know..........."do as I say and not as I do" right?
I'm the father of three teenage sons. I use that logic a lot myself.
Thanks man.
I appreciate your help.

Yes, I'm the one under the car, but not the one pouring the fluid. That was also two different fluid changes. Both a GM fluid. Just a different brand name.

i kinda have the same problem with my tranny. when i first began to drive the tranny shifts fine but after about 10-15 minutes it shifts hard , i just changed the filter and fluid about a week ago the car has 114500 on it.

Did changing the filter and the fluid fix your tranny problems

I'm terribly sorry. On my way home from work last night, I realized what you were stating when you said to be sure that you use GM transmission fluid. You meant fluid that was formulated for and recommended for use in GM vehicles, you were not saying that the fluid had to be a product produced by General Motors. I work on a lot of boat motors. In all of their repair manuals, they state that you have to use their products. Yamaha will not honor a warantee repair on an outboard if they determine that the 2-cycle oil you use is not Yamaha oil.
I'm sorry, you have done everything you can to help me out and I respond with criticism. It will not happen again.

Don't worry, I didn't take it that way. Question me if you wish any time
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