Trans slams into gear on first shift [Archive] - Forum


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10-24-2010, 10:39 PM
Hey guys, haven't been here in a minute, but I've come across an issue that's got me stumped. It's a 2004 GAGT w/ 99k on it

So, at 24k (about 1k after I got the car ;crap) my tranny crapped out on me. I found a 16k mile 4t45e and tossed it in there. Fast forward 75k mostly problem-free miles later, my replacement tranny starts acting up. The problem I'm having is that on the very first shift of the drive, the car hangs in first a little too long and then slams into second. It only happens on the very first shift of the drive, and none of the subsequent 1-2 shifts.
The only other transmission problem I've had is that when it rains out, I can't give the car too much gas or I get ridiculous spark retard, but I figured that would be one of the VSSs getting wet or something.
Last time I was underneath the car, I noticed a little atf residue around the outside of the trans pan. Could it be that I've lost enough trans fluid over the years to cause this problem? I'd check myself but both my sets of jack stands are underneath my partially disassembled work van, so I don't see them becoming availaible to pop the check bolt out any time soon. The color seems perfectly fine when i stick the end of a zip tie down the fill hole though.

Anyways, any suggestions?

Thanks in advance,


10-25-2010, 03:40 PM

10-25-2010, 06:20 PM
Well i would say change the trans fluid.. it might have a leak somewhere too in the tranny but not sure.. i have heard of problems like this before but not 100% sure on the fix.

10-25-2010, 08:01 PM
Changing fluid/filter may help some. It there are ANY leaks at all you could be running low levels, not a good situation.

Probable cause is the 1-2 piston getting 'stuck'. GM redid these at some point and also changed from plastic to metal. Cleaner fluid may help for a while. Swapping trannies via GM will get you all new parts and up-grades while other shops may not... Anyhow this is not a driveway repair. Other possibilities come to mind but I'd just do the maintainance thing first, maybe even dump and re-fill again 100 miles later or so - looking to get any and all junk out of the trans. Keep us posted - good luck!