Took my Yukon to dealership for a simple tranny fluid drain and fill, now undriveable

AJT123 · June 6, 2018

Hello fellow owners,

I have a 2003 Yukon (w/ 5.3) as my "beater", although it is my daily driver. It is beat up but mechanically in good condition. It has 122,000 miles on it. I went to the dealer, not some sketchy transmission shop, as I noticed the fluid is starting to look burned and it calls for it at 100k anyway, plus it's just a good idea to have your fluids swapped out.

I go to get the car back and it's stuck in third gear and the CEL comes on. Almost undriveable. Drove fine this morning, and for the past 15 years. Tranny shifts a little harder, but still fine.

Now, I either see one of two things happening here:

1. It's something silly and minor, some switch didn't get connected, easy fix

or....

2. They're going to tell me I'm SOL, blame it on something else and say I need a new transmission.

Why I am stressing here is because I really don't want to hassle with this dealership, and all that would entail, if they try to pull BS. I don't want to have to get into shouting matches with the service managers, etc. But bottom line is I paid $200 to get back an undriveable truck.

My truck drove fine this morning. When I got it back it was stuck in gear 3 and CEL on.

This is the premiere GMC dealer in Knoxville, and I always take my cars to dealers for transmission things bc dealers will stand behind their work.

What do some of you think? I'm thinking of going ahead and emailing the service manager.

Of course she said the transmission tech can't get to it until next week (who the hell did the work, then?). Didn't even offer a loaner.

Just my luck, why can't we have nice things?

Any educated guesses or just advice would be greatly, greatly appreciated.

I just wanted to do a simple drain and fill. I'm no mechanic but I do know cars, the best way to maintain a transmission with high miles is to drain and fill, every time. Forget flushing.

Bottom line is they F'd up bad.

desim8a · June 6, 2018

Do you have a way to check engine codes?

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AJT123 · June 6, 2018

No, I just left it at the dealer. Irritating to pay $200 to get back a truck that drove quite well to stuck in 3rd gear. I just wanted a drain and fill. This is like getting your oil changed and then your engine blows.

desim8a · June 6, 2018

I hear you man, it's frustrating. Is your engine running normally?

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AJT123 · June 6, 2018

10 minutes ago, desim8a said:

I hear you man, it's frustrating. Is your engine running normally?

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Yes, I only drove it a block or so, but the motor seemed fine. No missing or anything. Just alot of lag because it's starting out in 3rd gear.

Supreme Pizza · June 6, 2018

"Never have the transmission fluid changed". Its controversial, and many others will disagree - but I'm guessing you would agree with that statement at this point. If you want an explanation as to why this causes problems, just ask. Happy to provide info, but its trivial at this point.

mjm-1957 · June 6, 2018

Did they drop the pan and replace the filter? If they did they might have knocked one of the connectors off of one of the shift solenoids when they were putting the pan back on. Seen it many times before.It is a very close fit getting the pan back on around the engine pipe. Scan for codes and see if any shift solenoid codes are current.The default is third gear and full line pressure. An easy fix if thats the problem.

Supreme Pizza · June 6, 2018

41 minutes ago, mjm-1957 said:

Did they drop the pan and replace the filter? If they did they might have knocked one of the connectors off of one of the shift solenoids when they were putting the pan back on. Seen it many times before.It is a very close fit getting the pan back on around the engine pipe. Scan for codes and see if any shift solenoid codes are current.The default is third gear and full line pressure. An easy fix if thats the problem.

Good tip.

I have seen similar issues. Sometimes after a repair, people will forget to plug an electrical connection back in, or other simple issue. I have also seen repair shops sabotage parts to get more business. Then when you pay the $2500 for the repair, they un-do the sabotage and everything works great. I have seen my boss do this kind of thing many times when I was a kid working in repair shops. Its pure evil. That's what motivated me to be an independent mechanic. I have never screwed over a customer like that. All my ex-bosses have since gone bankrupt and closed up shop.

AJT123 · June 7, 2018

6 hours ago, starman8tdc said:

"Never have the transmission fluid changed". Its controversial, and many others will disagree - but I'm guessing you would agree with that statement at this point. If you want an explanation as to why this causes problems, just ask. Happy to provide info, but its trivial at this point.

No, I don't agree. To me, it's simple physics. It's not lifetime fluid or a "sealed" transmission, and it's a 15 year old truck that's had a fairly hard life, and the fluid has never been changed. I haven't picked up my boat yet but I anticipate a lot of towing this summer. In the owner's manual even it says to drain and refill it. Now a flush I would never, ever do. You want to slowly introduce the new fluid.

Rosco · June 7, 2018

It does sound like a solenoid issue. Smart not driving it. I would attempt to let the dealership fix it, not much can go wrong with a drain and fill pan drop as long as they did not "catch" the wiring harness on anything. On my 2001 Yukon I have to unbolt the tranny mount and jack it up about an inch to clear the pipe in order for the pan to come off.

If they offer to drop the pan and look at it that is 5 more quarts of clean fluid for you. Hopefully they find something simple.

Supreme Pizza · June 7, 2018

I have looked into this matter very thoroughly on multiple occasions over the years.

Benefits of changing the fluid:

1) The transmission MIGHT last longer with new fluid.

Disadvantages of changing the fluid:

1) Transmission might fail immediately, or sometime over the next year.

To me its just not worth the risk. If it ain't broke, don't fix it. I have talked to many transmission shops about it, and they all said the same thing:

If you know the service history on the trans fluid, and you know for sure that it was changed regularly - then keep changing it. If you don't know the history on the transmission, then LEAVE IT ALONE.

Problem #1: As the fluid gets old, the detergent stops working. Crud builds up on the inside parts. When you introduce new fluid, it loosens that crud up and it clogs the valve body.

Problem #2: If there are seals inside the transmission that are not sealing very well, the leaks get clogged by crud. New detergent in the fluid washes the crud away and the seal fails.

Problem #3: The new fluid will be more slippery than the old fluid, so if you clutches are weak at all, then you just caused the transmission to fail by replacing the fluid.

Problem #4: It was working just fine..... until you messed with it.......

Many people will agree with this. Many will not agree with this. There is no correct answer. I highly advise that you just leave well enough alone and drive it.

Supreme Pizza · June 7, 2018

As stated above, a well cared for transmission will definitely benefit from new fluid. An older transmission that has been neglected will die if the old fluid is replaced with new fluid. Imagine that your blood was replaced with a special new kind of blood that washes all the plaque off of your arteries. You would die almost immediately from a stroke or heart attack. Now if you used that special new type of blood from birth, you would be just fine, and probably have a better life expectancy. The transmission fluid detergent wears out and stops working. The new fluid is loaded with fresh detergent that washes the crud off the walls and clogs stuff, just like washing the plaque off of the arteries.

Change your fluid regularly from day one, or don't change it at all.

The new fluid ONLY causes problems in neglected transmissions. If you do a filter change on a neglected transmission, you want to save the old fluid, filter it - and put it back into the transmission.

I have had several transmissions fail in my life. All of which, I had replaced the transmission fluid without knowing the maintenance history. I researched it to find out why. I called many transmission shops, and researched the hell out of it. After I found out about the detergent issue, I replaced the fluid in new transmissions regularly, and I stopped replacing the fluid on vehicles with unknown history. Since I adopted this maintenance practice, I have had zero transmission failures in the last 20 years. One of my Suburbans has 253,000 miles on the original fluid - and the transmission works great. My other Suburban had a new transmission put in it just before I bought it, so I change that fluid regularly, and the transmission works great.

Its a counter intuitive issue - but how much research have you done, aside from looking in your owners manual or asking one repair shop?

You replaced the fluid, and now there is a problem. How many people do you think have had the exact some thing happen? Your transmission issue may just be a loose wire, and not all neglected transmissions fail from having new fluid. There is no 100% and there are exceptions to every rule. But from all the research that I have done, and all the HONEST transmission repairs shops that I have talked to say that you need to leave a neglected transmission alone.

Not everyone will agree with me or the many transmission specialists that I have talked to, but is it really worth risking your transmission?

Again, one of my Suburbans has 253,000 miles on the original fluid - and the transmission works great.

KARNUT · June 7, 2018

Back in the eighties my brother had an auto repair shop. He would refuse to do transmission fluid change. The worst was the C -4 Ford trans. Even low mileage ones.

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Supreme Pizza · June 7, 2018

Quotes from Google:

George Peters 7 months ago

Changing transmission fluid doesn't damage a transmission? Wanna bet? I had my transmission fluid changed and immediatly after it wouldn't drive out of the bay and I had to get a new transmission! It drove in the bay with no problem!

Rxonmymind 7 months ago

I once made the mistake of changing the transmission oil prior to our trip to Disneyland. Thinking I will get everything in Tip-Top shape a drain the fluid change the filter at 330k miles. Going up the Grapevine the transmission slipped and we were stuck. Haven't talked to three different shops who had no skin in the game but had Decades of experience they all said the same thing that is never change an extremely high mileage transmission with new oil. For whatever reason the oil that was in there was keeping everything together. $3,000 later I learned my lesson.

sefiroxx · June 7, 2018

Ditto starman,

Don't use the pressure fluid exchangers either that most stealerships will use. These will run new fluid in different directions, causing loose crud material to jam up valve bodies.

I have used the tranny pump for years to pump out old fluid while adding new fluid to change old and new transmissions. It entails disconnecting a transmission cooler line at the radiator or cooler, hooking up to a pail, run the car and while fluid is pumping out, add replacement fluid until you see clear fluid coming out.

Use synthetic as replacement.

As for your problem, sounds like you are stuck in limp mode. This is default when the trans is getting no power. Make sure the wire harness is plugged into the side, pull it and reset as well. Check fuses. After that, check dtc codes.

You could have a clogged valve/valve body. May need to pull and rebuild the valve body - but check limp mode symptoms first.