05 Tahoe only shifts when it leaks fluid

[Tboyle778]

I bought a used 2005 Tahoe about 15 days ago. All was good until about 6 days ago It suddenly stop shifting in mid drive. So I let it cool off and then again started to drive and stop shifting again. Now I grew up in an auto shop as my dads helper he was a BMW and foreign car mechanic as well as domestic car mechanic his whole life so I picked up a thing or two or more just from working with him and learning from him but the first thing I thought was oh boy the transmission has gone out. So then I looked around on the internet and YouTube and I found a video of someone saying that the specific transmission 4L60E stops shifting when a new filter is needed. I thought okay I could do this so I bought a filter and I replaced it . Fired it up went for a drive no problem continue driving for another 3-4 days not a problem except I was leaking transmission fluid because I forgot to tighten up some of the nuts so I go back underneath the Tahoe and I tighten them up all the sudden it stops shifting again. My question is that could there be a vacuum issue causing the transmission not to shift because it works fine when the transmission pan is loosened but it leads transmission fluid obviously which is not a good thing but I wonder if anybody else's experienced anything like this before or if anybody has any answers as far as the vacuum lines go?. Thank you for your time and responding .

 

[justirv]

I bought a used 2005 Tahoe about 15 days ago. All was good until about 6 days ago It suddenly stop shifting in mid drive. So I let it cool off and then again started to drive and stop shifting again. Now I grew up in an auto shop as my dads helper he was a BMW and foreign car mechanic as well as domestic car mechanic his whole life so I picked up a thing or two or more just from working with him and learning from him but the first thing I thought was oh boy the transmission has gone out. So then I looked around on the internet and YouTube and I found a video of someone saying that the specific transmission 4L60E stops shifting when a new filter is needed. I thought okay I could do this so I bought a filter and I replaced it . Fired it up went for a drive no problem continue driving for another 3-4 days not a problem except I was leaking transmission fluid because I forgot to tighten up some of the nuts so I go back underneath the Tahoe and I tighten them up all the sudden it stops shifting again. My question is that could there be a vacuum issue causing the transmission not to shift because it works fine when the transmission pan is loosened but it leads transmission fluid obviously which is not a good thing but I wonder if anybody else's experienced anything like this before or if anybody has any answers as far as the vacuum lines go?. Thank you for your time and responding .

1st off I'd look for any codes. When you say it "shifts fine", do you mean you can drive around and have normal upshift progression (1-2-3-4) and downshift (4-3-2-1)? When it stops "shifting", can you drive at all, and the trans stays in 1st gear, or you haveno forward (or reverse) movement? Or is it possibly in limp mode (3rd gear only)? The shifting in an '05 4L65e is electronic, and not controlled by vacuum. If you disconnect the trans connector you should be able to drive around in 3rd, if there are no internal problems. You had mentioned changing the trans filter; there is a small seal hiding up in the valve body where the filter slides into. If this is not removed, it can cause seating problems with the filter, as one would double-up the seal with the new seal installation. That may explain why the pan pressure/tension affects the operation when fully secured.

 

[Tboyle778]

1st off I'd look for any codes. When you say it "shifts fine", do you mean you can drive around and have normal upshift progression (1-2-3-4) and downshift (4-3-2-1)? When it stops "shifting", can you drive at all, and the trans stays in 1st gear, or you haveno forward (or reverse) movement? Or is it possibly in limp mode (3rd gear only)? The shifting in an '05 4L65e is electronic, and not controlled by vacuum. If you disconnect the trans connector you should be able to drive around in 3rd, if there are no internal problems. You had mentioned changing the trans filter; there is a small seal hiding up in the valve body where the filter slides into. If this is not removed, it can cause seating problems with the filter, as one would double-up the seal with the new seal installation. That may explain why the pan pressure/tension affects the operation when fully secured.

It is not throwing any codes. You may be right about the filter seating and the seal I'm going to go remove the filter again and double check thank you