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2019 12,320 Miles 6.2 HC Silverado Weird Issue (Slow start & C0021, P25A2 codes)

jgisonfire
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jgisonfire Enthusiast

jgisonfire

Posted
Posted

I've searched and found others who have had the codes above, but I wanted to see if anyone has run into what happened to me today.

 

I haven't driven the truck in a few days. It's sat in the garage in Southern Indiana with slightly above normal temps. This morning I walk out and attempt to remote start it (like I always do, because I love the sound the GM Performance exhaust makes LOL) and the engine attempts to start, turning over very slowly what sounded like less than 2 times. Concerned I unlocked the truck and got in. Using the push button the engine turns over very slowly again 4-5 times and then starts. When it starts my compass tells me it needs to be calibrated, my fuel gauge shows absolutely empty (I had at least 1/4 tank), and my check engine light comes on. I turned it off, exited the truck to reset things. Restarted, was still slower than normal turning over, but it started quicker. The fuel gauge was still on absolute 0 and the check engine light was on. I called the dealer to make an appointment, and checked the codes with a scanner. I had 2 C0021, and 2 P25A2 codes (I have all updates and TSB's done as confirmed by the dealer). 

 

I thought it might have been a battery issue, as my fuel gauge started going up as I was driving, finally getting to where it should have been by the time I got to the dealership, and the check engine light went off, because of course it did...

 

I spent 3 hours at the dealership, where they say they tested the battery, and all of the computers with nothing showing as wrong. The manager gave me his card and said to call his cell phone if the light comes back on and head in so they can test it when the light is on.

 

I guess my main question is does anyone here think this could be caused by the speed sensor staying on and draining the battery (even post TSB)? Or maybe something else electrical?

 

Thanks in advance for thoughts/options on this

  • 1 month later...
jgisonfire Enthusiast

jgisonfire

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If anyone is following along on this, it happened again on Sunday. Truck attempted to crank 1 turn over but no go. I waited to start it because the dealership was closed. I attempted to start it on Monday (not realizing the dealership was closed) and the truck wouldn't start. A bunch of messages came up on the screen (see below for the list in order). Truck was picked up by the tow truck this morning and taken to the dealership this morning. It's hooked up to a diagnostic machine overnight to see what's draining the battery and causing all these issues! 

 

Traction Control Off
Traction Control On
Brake System Failure - 62 MPH Top Speed
4WD Off
Brake System Failure - 62 MPH Top Speed
Service ESC
Service Parking Brake
Battery Saver Active
Traction Control On
Traction Control Off
Service ESC
Service Parking Brake

jgisonfire Enthusiast

jgisonfire

Posted
  • Author
Posted

I got the truck back today, with a brand new battery replaced under warranty. There was a bad cell in the original battery.

 

When I went to pick up the truck the check engine light was on. I went back in and they were going to see what was needed to fix it. After about 20 minutes (this is well after the main techs are gone) the guy comes up and tells me the codes are related to the DC to DC converter and since I need to be at work early in the morning, I could take the truck and return with it when I am ready. When I got home I wanted to see the codes, so I plug in my code reader and am SHOCKED to see 30 DTCs (14 different ones). The codes and what I could find on them are listed below. One of them has something on the NHTSA's website... It says GM wants to examine vehicles with these codes within 5 hours of Detroit.

 

B2B0E PIE0546 https://static.nhtsa.gov/odi/tsbs/2019/MC-10169366-9999.pdf
C0021
Right Front Wheel Speed Sensor Circuit Open Or Shorted To Battery
C054A
?? EBCM Control Valve Circuit - Limited Information
C0580
Right Front Actuator Circuit
P2534
Ignition On/Start Switch Circuit Low Voltage
P3051
DC/DC Converter Actuator Voltage Sensor Circuit 1 Low Voltage
P3052
DC/DC Converter Actuator Voltage Sensor Circuit 2 Low Voltage
P3055
DC/DC Converter Actuator Voltage 1 Performance
P3056
DC/DC Converter Actuator Voltage 2 Performance
P305C
DC/DC Converter Ignition On/Start Switch Circuit Low Voltage
P305E
DC/DC Converter Crank Control Circuit Low Voltage
U18A7
Lost Communication With Power Supply Transformer On Powertrain Expansion CAN Bus
U3006
Control Module Input Power 1
U3007
Control Module Supply Circuit 2
jgisonfire Enthusiast

jgisonfire

Posted
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Update this morning. Truck is dead again this morning... so now for the 3rd time the truck is going in for starting issues... I will continue to update in case anyone else is unlucky enough to have this happen to them.

jgisonfire Enthusiast

jgisonfire

Posted
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I got the truck back, something about replacing the T9 in the DC to DC converter was the problem according to GM Techs. It was actually done Friday morning, but the dealership wanted to make sure it was fixed this time. It's worked fine so far today... fingers crossed that stays the same!

  • 7 months later...
idle_liquid New Member

idle_liquid

Posted
Posted

How has it been running since?

 

My 2019 silverado is sitting dead in my driveway is less than 40,000km. Diagnostic codes are:

 

C0021 x 2 Right rear hydraulic release too long

P25A2 x 2

U0101 Lost communication with TCM

U0100 Lost communication with ECM/PCM

U0146 Lost communication with Gateway "A"

 

  • 2 years later...
  • 2 months later...
Jose616 Enthusiast

Jose616

Posted
Posted

I know this is an old thread, just hoping to revive it before starting a new one. I have the EXACT SAME issues, lights, and battery drain as the OP. Called local shop (since out of warranty) before heading to the dealer and they didn’t understand what the “T9 in the DC/to DC converter was. Anyone make any headway on this?

  • 5 months later...
TonyJ210 New Member

TonyJ210

Posted
Posted

I know this is an old thread, but I am just experiencing this exact issue and looking for a resolution if there is one.

Thanks in advanced.

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