2003 Tahoe Z71 won't move in Drive or 3rd

[76Nick]

Hello, I have a 2003 Tahoe Z71 with a 4L60. Has 140k on the clock. Previous owner said the trans was rebuilt but I have an odd feeling he lied. Anyway, my wife was pulling out of dunkin donuts today and she said she heard a clunk when it tried to change from 1st to 2nd and the truck stopped driving. She rolled it into the gas station next door. When I got there I noticed it won't go anywhere when its in Drive or 3rd. I drove it home in 2nd but it also will drive in 1st and Reverse. Any ideas or has anyone else had this issue before?

I just pulled the rear drivers axle over the weekend to change an axle seal so obviously I had to change the gear oil in the rear diff. Don't see how that would have anything to do with this though. I have also had an intermittent "service 4wd" message a few times but it went away and I haven't seen it in a couple weeks. Any help would be greatly appreciated. Thanks!

Nick

 

[S33k3r]

Sounds like transmission rebuild time.

 

[OR VietVet]

Basics first: Fluid level and condition? Maybe @rockola1971 can chime in and he will want to know what I just asked.

 

[rockola1971]

Fluid level and Color and does it smell burnt? Fluid should be red to pink in color, NOT orange/Brownish. If its burnt then youll know it. That is a smell no one forgets. Any tranny codes stored in PCM? Rule out the electrical faults after you see and smell the fluid. Transmissions do odd things when low on fluid or havent had their filters changed in a very long time.

 

[76Nick]

I will check again when I get home but last time I checked the fluid or seemed fine. Maybe slightly on the high side. But didn't seem orange or burnt. I don't have any transmission codes either, assuming if it was going to throw a code it would have done so right away. I will scan it again when i get home also. Hoping its not going to be a rebuild but I have a bad feeling.

 

[Mudsport96]

Well having 2nd and reverse means the sunshell is not broken.
Manual first and manual second mean forward clutches and overdrive clutches are ok. So.... it is a few possibilities. Check to make sure the plug on the trans is connected good. After that, it could be internal wiring.
This sounds similar to this link so have a read.

https://ls1tech.com/forums/automatic-transmission/1934122-4l60e-only-manual-1st-2nd.html

 

[76Nick]

Well having 2nd and reverse means the sunshell is not broken.
Manual first and manual second mean forward clutches and overdrive clutches are ok. So.... it is a few possibilities. Check to make sure the plug on the trans is connected good. After that, it could be internal wiring.
This sounds similar to this link so have a read.

https://ls1tech.com/forums/automatic-transmission/1934122-4l60e-only-manual-1st-2nd.html

Interesting....so this could potentially be a pressure switch. Ill scan for codes when i get home. And see what I come up with. I came across another post with a similar issue where there was nothing in drive but from park but if they started from manual 1 and then to drive it shifted normally. Should I try this or do I risk damage.or further damage to the trans?

I forgot to mention in the original post but before this happened shifting from 1-2 was a little on the hard side. Not sure if issue is related but this all happened when it was shifting from 1-2.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

 

[OR VietVet]

Interesting....so this could potentially be a pressure switch. Ill scan for codes when i get home. And see what I come up with. I came across another post with a similar issue where there was nothing in drive but from park but if they started from manual 1 and then to drive it shifted normally. Should I try this or do I risk damage.or further damage to the trans?

I forgot to mention in the original post but before this happened shifting from 1-2 was a little on the hard side. Not sure if issue is related but this all happened when it was shifting from 1-2.

Being new to the forum, I hope you remember, any time you post and ask for help, please post as much info as possible. Things like what you have been experiencing before the problems, previous work and by whom, what you checked or attempted to do and in chronological order. It helps all of us to help you. I hope you get the help you need here and it all comes out great in the end.

 

[Mudsport96]

I depends how mechanically inclined you are. I tend to think with 2nd and reverse working things may be mechanically okay.. maybe. Check codes, does it run okay other than that? A tps sensor can also cause goofy shifting, but typically also causes other driving issues.