Transmission might be toast.

11bDad · April 24, 2016

Took the first short road trip in my truck yesterday. Roughly 90 miles from home, going up a grade on the interstate, transmission starts slipping like hell. Running 70 mph, the tach shoots up to 3500-4000 rpm. As I'm slowing down, I'm trying to lightly apply the gas pedal and get moving again. Drop trans into M and slowly start to gain some speed. Temp shot up to 240 and then settled back down to 190. Exit the interstate, and proceed 6 miles to my destination. Truck won't shift any higher than 3rd gear. Load up my daughters stuff to bring home from college and head back (140 miles). Baby it on home running 70 and get off the interstate. Doesn't want to shift above 3rd again for the 3 miles to my house. WTF

Take it to a local GMC dealer & drop it off. Service advisor says something about high speed clutches, but he's only been there 2 months (Nissan experience). I know this isn't going to be a quick fix, so I inquire about a loaner. He says he needs to ask the Mgr. on Monday. Bought the truck from another dealer 25 miles away, but their service dept. is not on par with these guys. Truck is 7 months old and turned 10k miles on the way home.

TJay74 · April 24, 2016

I wouldn't worry, things happen. As far as loaner, per GM if the truck is going to be out of service for over 24 hours the dealer is to put you into another GM loaner vehicle until your vehicle is repaired.

11bDad · April 27, 2016

Picked the truck up today & although the ride home was only 3 miles, it appears to be shifting normally. The drive to work tomorrow (23 miles) should be a good shakedown test. Invoice states: "Found code P0741 "TCC system off". Removed and tested both the valve body and trans pump. Found Control Valve Body failed. Replaced Control Valve Body, fluid, and reprogrammed". Part number 24275873 is listed. We shall see.

11bDad · April 28, 2016

Same crap. Halfway to work & it starts all over again. Check engine light comes on & shifting is labored. Won't shift using Manual button, or shift into 6th.

ToesonTheNose · April 28, 2016

holy crap

Daryl Z71 · April 28, 2016

Sounds like something else is causing the part that they replaced to go bad...

11bDad · April 28, 2016

That part # appears to be the Transmission Control Solenoid. I asked the Service Adviser what is required for them to replace the transmission & he said there was a procedure they had to follow before that would be considered. I certainly understand that, and this will be attempt #2 to correct the issue. I will allow them the 3 attempts they are allowed to fix the problem. Hopefully they will get it repaired, and that will be the end of it.

HondaHawkGT · April 30, 2016

Yeah they ought to just give you a replacement after their quick fix failed. Unless they completely tear down the trans, there could be other issues hidden inside.

11bDad · May 5, 2016

Service guy at the dealership just called me back after having the truck back for 4 days to try and fix this issue. He tells me the trans tech has diagnosed it as 2 bad fuel injectors. Bad fuel injectors causing slipping, and erratic shifting? I guess anything is possible. The ball is in their court, so I just have to let them do their thing & hope they're right. I'll keep you posted.

HondaHawkGT · May 5, 2016

It's possible. The transmission will behave erraticly if the engine isn't running right. The engine and transmission control modules communicate with each other in order to coordinate engine power/rpm during shifts. One affects the other when something is wrong.

TJay74 · May 5, 2016

Could be possible, the system uses a driver demand table that is torque based as part of the shift logic.

11bDad · May 6, 2016

What you guys are saying makes sense. Truck was supposed to be ready this afternoon. Called the dealer around 4:00pm since I hadn't heard from him. He checks with the tranny guy who says he wants to play it safe and replace all 6 injectors. Naturally they don't have them in stock. Maybe ready on Tue. The loaner is ok (2015 GMC Acadia), but I just want my damn truck back.

morrislee · May 9, 2016

My tranny was slipping for the longest time during cold. Guess, what, after 6 month of going back and forth, a little $20 bluetooth ODB2 adapter found I have misfire at cylinder 7 and eventually it was triggering a code to let the dealer to fix it. after injector replaced, tranny no longer slips.

HondaHawkGT · May 9, 2016

My tranny was slipping for the longest time during cold. Guess, what, after 6 month of going back and forth, a little $20 bluetooth ODB2 adapter found I have misfire at cylinder 7 and eventually it was triggering a code to let the dealer to fix it. after injector replaced, tranny no longer slips.

Using the Torque app I take it?