The tranny in my 2000 Silvy has developed a very firm shift from 1st to 2nd. It really snaps into 2nd under normal driving. I haven't tried to get on it to see what it feels like under a heavier foot.

The tranny is stock with about 90,XXX miles on it, but has had to have some work done to it in the past. The prior owner had it done about 14,XXX miles ago. It had a trouble code of P-1870, the shop replaced the torque converter, did some sort of updates, and a reseal. It doesn't throw any codes, it just shifts very harsh into 2nd.

What could the problem be now?

 

Sounds like the trans is in "limp" mode where it increases line pressure. I suspect there is a code stored even if no SES light. Put a code reader on it or go to autozone and I bet there is a code set which should give you a clue.

 

Sounds like you have a broken 1-2 accumulator spring or an accumulator valve that is stuck in the valve body for the 1-2 shift.

 

Would the accum valve or accum spring give any codes, shown or stored?

 

I forgot to mention that today it drove fine with no shifting issues. Maybe the accum valve was sticking a bit? I'll run it by Auto Zone tomorrow and see if it has any codes in there, and go from there.

 

I do not believe that either would throw a code.

 

my trany did that for a bit, and the other day i lost second and first slips. so i would get on it as soon as posilble.

Whitch trany is the best to rebild. i have a 04sieara sbrc 4x4 with 5.3

 

04sierracanada, get with Vince @ FLT, I'm sure he can answer all your questions. His link for Finish Line Transmissions is over here >>>>>>>>>>>>>>>>>>>

My tranny seems to be acting ok now, it still hasn't repeated the problems. I'll look into the accumulator valve and accumulator spring to see what I find. Thanks for the help everyone.

 

My problem seems to be more intermittent, it came back after a small trip I took this weekend. No slippage or codes just slams into second, and I've also noted that the torque converter isn't unlocking in fourth when it does this. It will shift harsly into second go to third and then fourth, but after fouth I don't get that small RPM drop. Normaly at about 65 MPH I run around 1600-1700 RPM's, but when it acts up I get about 1900-2000 RPM's at 65 MPH. I have also noticed that it is has some sort of studder when it's in fourth gear.

Could this be a heat thing? Since I bought the truck I have installed a factory tranny cooler.

Should I just get a new tranny/torque converter or can I fix the problem with a few parts? The tranny has 90,XXX miles on it now, so a new tranny isn't too far in my future I guess!

Thanks for the help so far guys.