2020 GMC AT4 - Won't start, won't even attempt to turn over

[kushal]

i just went through that. my 2020 gmc sierra elevation. 

did exactly what u mention above and completly died. I locked my truck went inside and came back out now it Wouldn't unlock my door.

Then I used my key from fob to open it ... jump started the truck and it took 5 min to start. finally it started ....now i have engine check light on...also just got an email i bought it 30 min later that my truck has  antilock breaking system issue. but i dont think that should kill the truck completely.

 no way it could be the battery....monday will be taking it to the dealership. 

[bkpubman]

Has it happened again? Mine has happened 3x and the last time it would not start so I had it towed to the dealer and of course it started once there. The 2nd time I was able to start it in neutral. No codes have been active. When it is happening I cant start it with the FOB either and I have tried both, but since it goes through the whole process except for turning over I assume its not a FOB issue. Also when trying to use the FOB I can hear the fuel pump prime and a couple of other noises from under the hood but again no cranking over. Mechanics have mine now and hoping to replicate but no luck so far. They wondered if it could be related to the glow plugs or something, but its 90+ here and its only happened in the past couple of months so its been warm. Sounds lie yours happened when cold. This is really frustrating to have a new truck be useless and leave you stranded. Mine is also a 2020 2500HD AT4. 

[iambill]

I am having a similar problem with my 2020 AT4 HD Duramax.

 

On two occasions I have found the truck with completely dead batteries.  I had to use the key in the fob to open the door.  Dealer load tested batteries, checked alternator and for parasitic draw -- all ok.  It's an intermittent problem.  

[larry1982]

I've had the same issue with my 2020 Chev 2500 High Country. Went to start it via the push button, dash light up like a Christmas Tree then just turned off. After 30 mins, it fired up and the check engine light was on. I immediately took to the dealership and left in a loaner. 5 days later, they told me they had to replace a sensor for the exhaust system. 

 

30 days later, same thing happened. When I took it to the dealer this time, they had "no record" of the sensor they replaced and claimed they just cleared the codes. 

 

Came here hoping to find an answer. To this day, my check engine light comes and goes. Only have 7k miles on my truck but never can time to get it to dealer when it's on. Infuriating to spend that much money on a truck and have to deal with these issues. 

Edited October 9, 2020 by larry1982
Forgot to add something

[[email protected]]

Have a 2020 Denali HD. Just happened. Same thing check ecm check fuel check power steering etc. Fooled with if for twenty minutes then pulled fuse 78 for the ECM replaced it and fired right up. Took it to dealer can diagnose anything  Mine was on of the first built ordered it the day orders opened. Also have had rear window replaced back carpet and rear seat because of a leak. Also had a problem with steering like many on this forum. I took it to my tire guy he found two tires were defective. Dealer replaced them steering problems were gone. 

[Allen Bucher]

I had the exact same scenario.  Thank you for posting the idea to start with the remote!!  I was stuck in western Nebraska and a tow was a day away.

 

The truck started and the check engine light was on and on-star indicated some issue between the engine and transmission.  I drove it 200 miles to the dealer with no issues.

 

Took it to the dealer and the ECM was replaced.  So far so good!!

[Keenan]

On 4/17/2020 at 10:24 PM, powerhaulic said:

Had another no start the evening before scheduled appointment for recalls.

Drove in with the check engine light on, left it running within 20min the lead diesel tech had the truck in and read all the codes.

I left in the loaner, called me next, day diagnosed bad ECU, had truck back the following day.

All good so far

I am having this issue with my 2021 AT4 with 3000 miles on it.  Have you had the the problem since you replaced the ECU?

Thanks in advance.

[Harley Roberts]

On 2/20/2020 at 9:37 AM, CO 2020 GMC AT4 said:

Twice now I go to start my 2020 GMC AT4 Dsl after it running fine throughout the day and nothing but errors.  I select the Start button and it acts like it is going to start as the dash lights up, then starts clicking and running through a bunch of error codes, from low fuel to other sensor issues.  Runs through the errors then just clicks and shuts down.  Then it trys again, showing the same errors. 

 

It happened first time in December.  I tried for 30 minutes to get it to start without any luck, then walked away and from about 50 feet hit the remote start and it fired right up.  I took it immediately to a dealer and they cleared the codes but could never duplicate it.  Said the first relay it came to was throwing a code and blocked the rest from letting it start.  Took it the next day to my local dealer and they couldn't do anything as the codes were cleared, but reviewed the printout from the dealer that cleared to codes and said they have never heard of the issue and was probably a fluke and would never happen again....  Their suggestion was to remove the battery terminals and touch them together, shorting out the system and resetting the computer....seems strange. 

 

Yesterday, it did the same thing.  Tried for over thirty minutes, and even the remote start would not work.  I didn't try to remove the terminals as it was freezing and 40MPH winds.  I went back in to the gas station and gave it some time, came back out and hit the remote start and it finally started up. 

 

Anyone else having this issue?  Any ideas on a resolution?

 

Getting tired of GM at this point.  My 17 and 18 had the lurching issue at altitudes from 5-6k feet, finally got a repurchase from GM on the 18.....

 

Thanks for any advice

 

Shane

Hi Shane. I have a 2020 GMC AT4 Duramax 6.6 litre. I bought it last June 2020 and today my truck done the same as yours. I tried starting it with the OnStar app and with the key fob but no luck. I tried a few times and then gave up. I tried again about 5 hours later and low and behold it started. Very confused about it. Have you heard of anyone else having this problem and did you have any luck finding out the problem? Hope to hear back Harley

[CO 2020 GMC AT4]

Harley

The dealer found a bulletin on this, said they updated the ECM and performed three other recalls at the time.  I have not had this issue since.  (If your dealer doesn't know what to do, they can call Fuoco in Grand Junction, CO.  They should be able to help.

 

For the last 6 months I have had a brake squalling issue, they replaced once under a recall/bulletin but put the same low friction pads on and less than 1000 miles its doing it again.  They said just drive it, they don't have a fix, GM won't let them put in high friction pads....

[Harley Roberts]

3 hours ago, CO 2020 GMC AT4 said:

Harley

The dealer found a bulletin on this, said they updated the ECM and performed three other recalls at the time.  I have not had this issue since.  (If your dealer doesn't know what to do, they can call Fuoco in Grand Junction, CO.  They should be able to help.

 

For the last 6 months I have had a brake squalling issue, they replaced once under a recall/bulletin but put the same low friction pads on and less than 1000 miles its doing it again.  They said just drive it, they don't have a fix, GM won't let them put in high friction pads....

My truck is going in on Saturday to GM, so I’ll definitely bring this up with them. Thanks fo the feedback I really appreciate it.. I haven’t had any brake issues with mine yet..

Edited April 5, 2021 by Harley Roberts

[Stephen Reich]

I have the 2020 At4 diesel same issue. At dealer now and all codes etc are normal. All weekend it went from no start with everything haywire to start with engine light on and u0100 and p0700 codes then all clear no engine light no codes. This after I went through hell with 2020 Sierra Denali diesel exhaust filter regen issue to the point I finally traded it fir high book and $5000 from GM to get this truck. Looks like my last $80000 purchase from GM. Going to move to Ford 

[Carlos_08tx]

2020 At 4 just died on me would even crank over. Called towing company and still cover under warranty. Dealership found metal shaving chunks in the oil pan. They saying all my rod and pistons and engine block are done. They will be replacing it with a whole new engine.

[Brandonb0013]

For what it's worth, I've had this happen now twice in the last three weeks.  The last time I had to get it towed, the first time it eventually started after an hour or so.

 

Regardless, the dealership first said it was the alternator (they replaced), that didn't fix it.  Then two days after this the Service 4WD popped up, I brought it back in, they found a loose ground cable (G132).  Tightened and it fixed it.  

 

Fast forward to a week ago and wouldnt start, same issue as described in the original post as well as the first time it wouldn't start.  This time at a different service center they found the same G132 cable had a "broken bracket" on the engine side of the cable.  

 

There is a techlink article here that was created in December 2019 (before the 3.0L was widely available), that states the loose ground cable problem as well as the affected vehicles (not the 3.0 because not known at the time I'm sure).

 

Also attached are images the last service center sent me.  Here is a google photos link showing what is happening at the DIC when not starting.  I plan to fix these cable ends in place "permanently" one way or anther...

a44daab6-e9dd-46d2-af66-d9b3740649db.jfif 02145852-99cc-4ea6-b495-bdcd3514efb6.jfif

[srileyathens]

So did the battery ground connection fix the issue long term? My 2021 Denali diesel did this and garage said it was a lose ground connection, the 132 connection

[svachon]

I am experiencing the exact same problem with my 2020 GMC 6.6L Diesel.  But mine has not been able to start for over 24 hours.  I'm having it towed to my local GMC Dealer this morning.  Very frustrating.