" Reduced acceleration" warning / CEL

[BrokerThis]

This just happened ..... seems like the trans isn't shifting into gears like it should and running high. Anybody experience?

'22 denali - dmax

 

[BrokerThis]

Might need to move this to "engine & drivetrain section" .... here's the pop up when trying to put into neutral

 

[UsualSuspect]

I know someone in a 21, same issue, it went to the dealer yesterday. They were told it's either a transmission solenoid, or the transmission needs to be replaced, they can't get to it for 2 weeks.

 

[BrokerThis]

I got a call and email out to my service rep at the dealer. I sent him these same pics but haven't gotten a response back yet. Thanks for that insight, hopefully the dealers around here won't be as backed up for 2 weeks if that's the case. Of course I'll keep the thread updated as things progress.

I think the Denali is jealous that I was working on the Trans AM .... and wanted me to give her some love too. Haha

 

[BrokerThis]

Little update: So on my trip back home after dinner.... the CEL is still on but the transmission seemed to be shifting like normal, and when putting into neutral that service message doesn't pop up.

Still concerned, and need the dealer to diagnois the CEL and whatever else... kinda sorta want the transmission to go back into the mode it was when this happened when getting to the dealer and leaving the rig running so they experience it first hand.

 

[WalleyeMikeIII]

Maybe hit the onstar button and ask for a remote diagnostic? Check the vehicle status on your MyGMC app. Both of these will let you know what codes are posted.

You still need to get it in

 

[BrokerThis]

@WalleyeMikeIII rig gotta be turned on to check from the mygmc app?

 

[WalleyeMikeIII]

@WalleyeMikeIII rig gotta be turned on to check from the mygmc app?

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Don't think so...kind of odd that you can have a Check Engine and a Transmission Message and have not have something popping up in the diagnostics.

 

[BrokerThis]

Even with rig running app doesn't show. Here is the onstar diagnosis. Waiting on dealer to get back with me still (shocker... I know ....)

 

[BrokerThis]

Go figure. Dealership tells me to bring it In tomorrow and they got a loaner for me. Start up the rig and CEL is off. Classic.

 

[WalleyeMikeIII]

But, you are good w/ that diags report!!! They gotta believe you. Guessing there will be history codes too

 

[BrokerThis]

Ill be dropping it off tomorrow regardless. But one would think your statement is logical and true.... but these lazy ass dealers/shops nowadays are like "oh we can't duplicate it or see anything wrong, so just wait for it to happen again and bring it to us when it's actively going on"

 

[BrokerThis]

Here was the codes dealer pulled up from their system. Sitting n waiting for diagnosis. They gave me a brand new Acadia denali for a loaner, so that was courteous of them.

 

[ESTTahoe]

Have you heard back what was the issue?
I have 2021 Tahoe High Country and last week encountered a similar issue. While driving on the highway, transmission suddenly stopped shifting higher gears and felt like on Neutral. "Reduced Acceleration" message and CEL. Arrived home and next morning the reverse gear stopped working. Took it to service shop but haven't heard back anything so far...
Located in Estonia, Europe with no official GM dealership for Tahoe. Imported car so I purely relay on the technicians & mechanics in the local shop (they seem to be experienced though with US made cars).

 

[BrokerThis]

Haven't heard back from my dealer yet. Dropped off last Friday.... as soon as i get it back, I will be posting the report and any information they give me to help others out that might run into this issue as well.

 

[DuraYuk]

Haven't heard back from my dealer yet. Dropped off last Friday.... as soon as i get it back, I will be posting the report and any information they give me to help others out that might run into this issue as well.

Based on those codes it's probably the solenoid. They will replace it.

 

[BrokerThis]

Dealer update today " haven't gotten to look at it yet. Both the diesel and trans techs are backed up" ... supposedly my rig was 4th in line for diagnosis when dropping it off friday.. seems weird they wouldn't be able to accomplish one vehicle a day if that was true .... but maybe they also knew it was going to take a pretty long time, which is why they put me in a brand new Acadia denali for the loaner. Who knows! Will update as it comes along though.

 

[DuraYuk]

Dealer update today " haven't gotten to look at it yet. Both the diesel and trans techs are backed up" ... supposedly my rig was 4th in line for diagnosis when dropping it off friday.. seems weird they wouldn't be able to accomplish one vehicle a day if that was true .... but maybe they also knew it was going to take a pretty long time, which is why they put me in a brand new Acadia denali for the loaner. Who knows! Will update as it comes along though.

Its possible but even for something simple they won't jump the line as it won't be fair. We never did when I worked as a tech. First come first serve.

 

[BrokerThis]

Just got it back and they replaced a valve. Will update this if it happens down the road. Hopefully this will be able to help anybody out in the future and doesn't happen to me again!

 

[buhamad112]

Just got it back and they replaced a valve. Will update this if it happens down the road. Hopefully this will be able to help anybody out in the future and doesn't happen to me again!

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Hi, does this issue resolved with valve replacment ? did you get the issue again ? i am still suffering of this issue and the dealer dont know how to diagnosis the issue. if this is the solution i am going to drop your report to them to do the same. appreciate your reply.