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

CO 2020 GMC AT4
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CO 2020 GMC AT4 Enthusiast

CO 2020 GMC AT4

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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

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powerhaulic
powerhaulic

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

Tomato Enthusiast

Tomato

Posted
Posted

Haven't had that issue, but could it simply be a loose ground or primary positive battery cable?  I've experienced similar issues as a result.

brianf60 Enthusiast

brianf60

Posted
Posted
2 minutes ago, CO 2020 GMC AT4 said:

 Their suggestion was to remove the battery terminals and touch them together, shorting out the system and resetting the computer....seems strange.  

Sorry Shane I can't help much. As a mechanic I find this response from the dealer to be ridiculous. Does this issue happen with both key fobs? Have you tried placing the fob in the section between the 2 front cup holders? This is the location used when the battery on the fob is dead. It will be able to pick up the key when placed there even if the battery in the fob is dead. (Location may very. This is where it is in my 2019 Elevation with center console)

CO 2020 GMC AT4 Enthusiast

CO 2020 GMC AT4

Posted
  • Author
Posted

Thanks for the feedback.  I'll check the cables and try placing the FOB there if it happens again.  I'm usually on the road when this happens and leave the other FOB at home.  I'll swap them out and see if I have the same issue.  Picked up the truck in October 19, around 6k miles. 

 

Other than this issue, I really like it...

newdude Senior Enthusiast

newdude

Posted
Posted (edited)
2 hours ago, 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

 

A couple of questions if I may...

 

Dsl...I assume you have the 3.0 Duramax?  Do you live in a cold climate?  Do you happen to know what trouble codes the truck set?  Is this happening on cold starts or even after its warmed up and has been running?  

Edited by newdude
CO 2020 GMC AT4 Enthusiast

CO 2020 GMC AT4

Posted
  • Author
Posted

Newdude

 

Thanks,  Should have said this initially:  2020 GMC 2500 AT4, 6.6 Diesel, Crew Cab standard bed.  No modifications except B&W Ball and a folding bed cover.

 

Yes, I live in Western Colorado, so cold but the days it occurred have not been too bad.  It is happening after I have been running the vehicle, then stop for fuel or to return phone calls, so short amount of time turned off.   Have not been towing either time. 

Found the printout from last time,  6 pages of issues:  Most seem related to the Engine Control Module - No Communication

Serial Gateway Module, no communication, Power Steering Module, lost communication with Engine Control Module, repeats for Transmission, Transfer Case, Body control, Chassis Control, Electronic Brake Control, etc...

DTC Display codes...U0100, U0422,

 

DLC Pin 6, 14 or 12,13 , 1 or 3,11

 

Called the dealer first thing this morning, they were going to discuss but still no answer...Just started it up, like nothing ever happened, well except the check engine light...

 

newdude Senior Enthusiast

newdude

Posted
Posted
1 hour ago, CO 2020 GMC AT4 said:

Newdude

 

Thanks,  Should have said this initially:  2020 GMC 2500 AT4, 6.6 Diesel, Crew Cab standard bed.  No modifications except B&W Ball and a folding bed cover.

 

Yes, I live in Western Colorado, so cold but the days it occurred have not been too bad.  It is happening after I have been running the vehicle, then stop for fuel or to return phone calls, so short amount of time turned off.   Have not been towing either time. 

Found the printout from last time,  6 pages of issues:  Most seem related to the Engine Control Module - No Communication

Serial Gateway Module, no communication, Power Steering Module, lost communication with Engine Control Module, repeats for Transmission, Transfer Case, Body control, Chassis Control, Electronic Brake Control, etc...

DTC Display codes...U0100, U0422,

 

DLC Pin 6, 14 or 12,13 , 1 or 3,11

 

Called the dealer first thing this morning, they were going to discuss but still no answer...Just started it up, like nothing ever happened, well except the check engine light...

 

 

Man that sucks.  Something is dropping out somewhere big time if its losing communication like that.  It could be something as simple as an intermittent bad battery cable, terminal tension, etc., or it could be a module failure.  Unfortunately every single module has to shake hands on these new cars/trucks otherwise $hit can hit the fan.    

 

Any idea what codes they found that are turning on the check engine light?  Typically a communication code won't turn the light on, but if there are others related or that are causing it ( a P type code like a P0300), those will.

georgia 2500 New Member

georgia 2500

Posted
Posted

My 2020 Silverado would not crank, had both batteries replaced and now one battery is charging at 12.4 and the other is charging at 14.4. This does not sound good for long term battery care. The first 2 batteries lasted 3 months. That's how I found out that there is actually a key in the FOB. That's the only way I got in the door it was so dead. 

  • 3 weeks later...
powerhaulic Enthusiast

powerhaulic

Posted
Posted
On 2/20/2020 at 11:37 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

I have no advise for you, but in the same boat.

I have had many P0700 general transmission codes set the light. Each and every time there have been multiple loss of communication codes.

The no start with the same dash light conditions you speak of has occurred.twice in 8000mi

 

Dealer has not been able to duplicate, of course.

There is no issue running or shifting, and I tow 17k 5th wheel. But sure don't like wondering if it will start......

  • 4 weeks later...
powerhaulic Enthusiast

powerhaulic

Posted
Posted

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 :)

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