Brand New Truck, DTC's, CEL, and -NO- message in the DIC that it might be dangerous to drive!

ember1205 · December 23, 2023

Welcome to the latest episode of GM doesn't understand how to write software.

2024 Silverado 1500 RST, 4WD, Crew Cab

Truck has about 1100 miles on it and last night it threw a CEL - solid, not flashing. When I got home, I grabbed my OBD connector and pulled the code information with my phone app. Two codes were set as follows:

U0121 - Freeze Frame: 47 (lost communications with anti-lock brakes)

U0418 (Invalid data received from brake system)

These two codes set the CEL and give the impression that actually driving the truck could be hazardous, yet there was NOTHING shown in the dash (BTW, GM - smart move to bury the CEL in the bottom right corner of the dash where the spokes of the steering wheel hide it from view).

There are two additional pending codes as follows:

U2418 (Unknown trouble code)

U2419 (Unknown trouble code)

Absolutely no clue what could be going on here, pretty much ZERO meaningful information for any of the codes except the very first one, but NOTHING in the current generation of trucks. The good news is that I already have an appointment for a myriad of issues that the dealer needs to address that were not right from day 1. The bad news is that it's two weeks away.

I cleared the set codes and the CEL went away. I will be driving the truck and monitoring the status but I'm wondering if anyone has any thoughts on what might be going on here. I hadn't opened a case with Chevy for the various issues to be looked at in two weeks, but I WILL be opening a case with them now.

Sigh.

Transient · December 24, 2023

I'll wager electrical gremlins. GM is notorious for them with new vehicles. A few thousand miles and they'll go away. It's happened to me on several new Chevys. Anyways seems to fix itself. Nonetheless, stay vigilant. And, you probably shouldn't clear codes if you want the dealership to take you seriously. If they can't see it, it didn't happen. #1 excuse they like to give the customer? "Cannot duplicate problem."

ember1205 · December 24, 2023

7 hours ago, Transient said:

I'll wager electrical gremlins. GM is notorious for them with new vehicles. A few thousand miles and they'll go away. It's happened to me on several new Chevys. Anyways seems to fix itself. Nonetheless, stay vigilant. And, you probably shouldn't clear codes if you want the dealership to take you seriously. If they can't see it, it didn't happen. #1 excuse they like to give the customer? "Cannot duplicate problem."

Since GM felt it was wise to bury a potential safety issue behind the anonymity of the CEL, I did what I ultimately felt was appropriate in clearing the codes. My safety is more important than their ability to read an active code. Besides, they are still present as "historical" codes.

And, while I agree that "electrical gremlins" plague new GM vehicles, what I found with my car was that it ultimately traced back to a bad (AGM) battery. For all of the so-called enhancements and benefits that AGM batteries are supposed to bring, they sure do seem to be the source of an awful lot of issues...

Trotorx2 · December 24, 2023

I had some warning messages show up on the DIC but no CEL. Mine were about the steering and some saying to open and close the windows. Mine started as a slow to engage the starter after pushing the start button. This was at around 2000 miles. I took it back to the dealer and they replaced the battery. So far the steering message and the windows message hasn't come back but the start delay is still there. I agree I think the factory battery isn't very good.

repairman54 · December 27, 2023

Today's batteries are all made with recycled lead. Only a few are made without recycled lead. That's one of the reasons for poor battery life. That and the manufacturer also.

ember1205 · December 27, 2023

41 minutes ago, repairman54 said:

Today's batteries are all made with recycled lead. Only a few are made without recycled lead. That's one of the reasons for poor battery life. That and the manufacturer also.

Have any reference links to read up on that?

redwngr · December 27, 2023

On 12/24/2023 at 2:41 PM, Trotorx2 said:

I had some warning messages show up on the DIC but no CEL. Mine were about the steering and some saying to open and close the windows. Mine started as a slow to engage the starter after pushing the start button. This was at around 2000 miles. I took it back to the dealer and they replaced the battery. So far the steering message and the windows message hasn't come back but the start delay is still there. I agree I think the factory battery isn't very good.

You can 'bump' and release the start switch.

Signal goes to BCM.

When it has completed whatever checks it does it sends signal to ECM, which completes whatever checks it does, on a diesel it also runs the glowplugs for the time suitable to current ambient and engine temperature.

Then it sends start command to fuel system and to starter.

It is NOT necessary to hold button (or key) while this is going on.

GM's have had 'bump and release' starting systems for many years.

ember1205 · December 27, 2023

1 minute ago, redwngr said:

You can 'bump' and release the start switch.

Signal goes to BCM.

When it has completed whatever checks it does it sends signal to ECM, which completes whatever checks it does, on a diesel it also runs the glowplugs for the time suitable to current ambient and engine temperature.

Then it sends start command to fuel system and to starter.

It is NOT necessary to hold button (or key) while this is going on.

GM's have had 'bump and release' starting systems for many years.

Are you basically just outlining the starting procedure? Or is this for something specific? Not sure I'm following the reasoning for it being here?

redwngr · December 27, 2023

3 minutes ago, ember1205 said:

Are you basically just outlining the starting procedure? Or is this for something specific? Not sure I'm following the reasoning for it being here?

See post I responded to.

Trotorx2 · December 27, 2023

10 minutes ago, redwngr said:

You can 'bump' and release the start switch.

Signal goes to BCM.

When it has completed whatever checks it does it sends signal to ECM, which completes whatever checks it does, on a diesel it also runs the glowplugs for the time suitable to current ambient and engine temperature.

Then it sends start command to fuel system and to starter.

It is NOT necessary to hold button (or key) while this is going on.

GM's have had 'bump and release' starting systems for many years.

I know how the start button works. After it has started and ran awhile it starts as soon as you push the button. It is getting slower and slower to start like before I took it to the dealer.

Ember1205, sorry for the side track.

ember1205 · December 27, 2023

9 minutes ago, redwngr said:

See post I responded to.

Yeah, I had looked at that and still wasn't following what specific item it may be addressing.

repairman54 · December 28, 2023

On 12/27/2023 at 8:37 AM, ember1205 said:

Have any reference links to read up on that?

Odessey batteries are my go-to for replacements. Pricey but they last. 10 yr. old one in my Harley and still strong. Put one in my standby generator also as I got tired of other brands only lasting 3 yrs. It's in there for 5 yrs now.

Put one in my old '11 Tahoe, still good after 5 yrs, traded it in for my Silverado so I don't know how long that one will last.