Idle relearn / throttle body cleaning

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Doubeleive

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I mean I’m driving it until it really starts to go out, it’s my errand car, I’ve put 1500 on it or more so far.

Unfortunately I’m having troubles selling it. It’s financed, and I have it on a 6 year loan, i was honest and I listed the issues it has and im asking at least $13.5k…

I feel like someone who really likes Tahoes and has a lot of sore turn and knowledge can put time into this. I was lookin for something solid and reliable, But I just need something smaller and cheaper. It’s pretty simple, my first time at the dealership and I folded. I guess it happens I realize that now.
that's going to be a tough sale
you might be better off just going with a used transmission
been there done that, pick up a side gig for extra money
 
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I mean I’m driving it until it really starts to go out, it’s my errand car, I’ve put 1500 on it or more so far.

Unfortunately I’m having troubles selling it. It’s financed, and I have it on a 6 year loan, i was honest and I listed the issues it has and im asking at least $13.5k…

I feel like someone who really likes Tahoes and has a lot of sore turn and knowledge can put time into this. I was lookin for something solid and reliable, But I just need something smaller and cheaper. It’s pretty simple, my first time at the dealership and I folded. I guess it happens I realize that now.
Gotcha, you're in a very tough spot unfortunately. You mentioned delayed upshifts from first to second gear - that's either pcm/techm, solenoid or valve body.

Fastest way to diagnose is to have a transmission (someone who knows the 6l80e very well) take it on a test drive with a two way scan tool, observe it's behavior and command shifts via the scan tool to see how it responds. If the command transmits successfully but the shift doesn't happen, the problem is in the transmission command and control body complex (TEHCM and/or VB). If the shift happens but clunks, slips, neutrals then the problem is inside the transmission.

If its just a valve body/tehcm issue you may be able to get it fixed for under $1500. If there's internal damage, it will obviously be much more.
 
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I second @Doubeleive 's suggestion of a used trans with the caveat it comes with a decent warranty and has less than 70k miles and you can do the swap yourself (if it has to come out and a shop does it, youre paying twice).. Otherwise you will be back to square one. I have built several used 6L80es. Before i got them in, some lasted a while (year+) while others crapped out within a couple months.

IMPORTANT: You will need to acquire one of the same year and that has the same TEHCM operating software (OS) as yours. The TEHCM OS id number can be found on the TEHCM itself (see pic below). That ID number matches the techm to the vehicle pcm and must be matched (the TEHCMs are NOT vin locked). Otherwise the PCM itself will have to be reflashed with the appropriate software.

Lastly, you will still need to have a fast adapt relearn performed regardless of what you do before you try to drive it.

TEHCM ID
IMG_7400.jpeg
 
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iboughtatahoe23

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Gotcha, you're in a very tough spot unfortunately. You mentioned delayed upshifts from first to second gear - that's either pcm/techm, solenoid or valve body.

Fastest way to diagnose is to have a transmission (someone who knows the 6l80e very well) take it on a test drive with a two way scan tool, observe it's behavior and command shifts via the scan tool to see how it responds. If the command transmits successfully but the shift doesn't happen, the problem is in the transmission command and control body complex (TEHCM and/or VB). If the shift happens but clunks, slips, neutrals then the problem is inside the transmission.

If its just a valve body/tehcm issue you may be able to get it fixed for under $1500. If there's internal damage, it will obviously be much more.
What’s a two way scanner.
 

iboughtatahoe23

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I second @Doubeleive 's suggestion of a used trans with the caveat it comes with a decent warranty and has less than 70k miles and you can do the swap yourself (if it has to come out and a shop does it, youre paying twice).. Otherwise you will be back to square one. I have built several used 6L80es. Before i got them in, some lasted a while (year+) while others crapped out within a couple months.

IMPORTANT: You will need to acquire one of the same year and that has the same TEHCM operating software (OS) as yours. The TEHCM OS id number can be found on the TEHCM itself (see pic below). That ID number matches the techm to the vehicle pcm and must be matched (the TEHCMs are NOT vin locked). Otherwise the PCM itself will have to be reflashed with the appropriate software.

Lastly, you will still need to have a fast adapt relearn performed regardless of what you do before you try to drive it.

TEHCM ID
View attachment 400377
I second @Doubeleive 's suggestion of a used trans with the caveat it comes with a decent warranty and has less than 70k miles and you can do the swap yourself (if it has to come out and a shop does it, youre paying twice).. Otherwise you will be back to square one. I have built several used 6L80es. Before i got them in, some lasted a while (year+) while others crapped out within a couple months.

IMPORTANT: You will need to acquire one of the same year and that has the same TEHCM operating software (OS) as yours. The TEHCM OS id number can be found on the TEHCM itself (see pic below). That ID number matches the techm to the vehicle pcm and must be matched (the TEHCMs are NOT vin locked). Otherwise the PCM itself will have to be reflashed with the appropriate software.

Lastly, you will still need to have a fast adapt relearn performed regardless of what you do before you try to drive it.

TEHCM ID
View attachment 400377
not sure what fast adapt relearn and all that is. I don’t own a computer. I’ve been asking around for people in my area to see if they would help me with my transmission and no luck.

And selling it has been rough to.
 

iboughtatahoe23

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Probably end up taking out another loan to fix it. I don’t see myself repairing or replacing a transmission, and I can’t be without a car. I worked to hard not to just be scammed by a dealership.
 
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Too bad. If he had more self-confidence he could rebuild the valve body and TECHM on his kitchen table.
Yep...the valve body/TEHCM complex looks intimidating at first glance to those not familiar but it's really one of the more straight-forward valve bodies to overhaul out there. Simply keeping organized and taking ones time is usually all that's needed to do it right (well that and an inch-lb torque wrench and information on the tightening-torquing sequence for each half). My 6L80E video series will give him (and anyone else) a really good look at the process and what it takes to work on these transmissions (it's one of the "easier" GM transmissions to work on - a lot less cumbersome/tedious compared to the 4L80E, IMO). ...Replacing the whole assembly is even easier (six starfish (inverted TP50) and lifting up on the pass through case connector lock) and it's out. Once done, he would just need someone w/a bi-directional scanner w/adaptation reset functionality to do the 'relearn'. A mobile tech can do that and charge maybe like $100-150 or so.

At the same time, he's in a tight spot; spent 65% of his gross annual income on the vehicle, got ripped off/misled in the process which really sucks and I feel bad for him. And if something goes wrong, its only going to make it worse. If he was in Vegas, I'd offer to assist with the vehicle/transmission at a lower cost than otherwise charge as I was in his exact same position when I was his age (I'm guessing he's 19-23 years old) so know exactly how it feels.

Probably end up taking out another loan to fix it. I don’t see myself repairing or replacing a transmission, and I can’t be without a car. I worked to hard not to just be scammed by a dealership.
That's probably the best course of action for you...It didn't occur to me that you may already have a loan on it (I assumed you bought it cash) but even though you're incurring more debt, you know you will have a reliable vehicle that you like going forward as the only other major systems that could fail with big $$$ consequences are the engine and rear end (and even those can be remediated with good used replacements). Other stuff you can probably do yourself with guidance from the factory service manual, this forum and/or YouTube.

Like someone else said, take on a second job/side gig for a while to help you make ends meet, at least until your primary job pays more or you find a higher paying job in the near future.

Keep us posted on how things go.
 
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992dr

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Probably end up taking out another loan to fix it. I don’t see myself repairing or replacing a transmission, and I can’t be without a car. I worked to hard not to just be scammed by a dealership.
This really sucks, I feel terrible for what you are going through.
Where are you located? Might be a long shot but maybe someone on the forum is local and can guide/give you a hand.
Also, don't be intimidated by the internals of the transmission. I felt the same way, granted I have 4l60e but it is none the less intimidating. Do a sh*t ton of research, subscribe to Nicks channel and take your time. Remember it's only nuts and bolts :)
I know there's plenty of guys on here who would help if you wanted to start a rebuild thread.
Either way, keep us all posted and good luck.
 

Geotrash

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Sounds like most of us have been right where he's at, and now 25 years later (in my case), I have learned the skills to do most anything necessary with my vehicles and it's wonderful to not feel beholden to a shop. The best way to learn is to dive in - especially when you have the help of people who know these trucks.

@iboughtatahoe23 please do tell us what city you're in. If you're anywhere near Richmond, VA, add me to the list of people who are willing to help you out. Get the transmission squared away and that truck will go 400K miles if it's relatively rust free.
 

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