2021 diesel Tahoe engine turn off when driving

[dbphillips]

2021 ST Tahoe diesel 4wd.
48,000 miles

No problems until while driving city streets speed my Tahoe’s engine turns off, shifts to neutral, electronics stay on.

I have to put flashers on, pull over to a full stop then restart the engine. It always cranks right up like nothing happened. There are no other symptoms before or after. The incident does not trigger any engine error codes at the dealership.

Any suggestions?

Misrouted harness and subsequent wear. Look it up in recalls. In particular look near the alternator bracket. Do you ever get weird dashboard messages regarding brakes and cruise control and collision avoidance system? Should get some codes, but if the ECM has a power interruption, maybe not.

 

[Tylerldurden]

Hello all and thanks for your help. I think the issue was fixed. After checking all the grounds for the 3rd time a tech finally found (hopefully) the issue. A connection pin for one of the grounds was bent up and didn’t have proper contact and the bolt was loose. The tech said it looked hand tightened. It’s been a few days and So far so good.

 

[Tylerldurden]

Thanks everyone. It’s still happening. First we fixed a ground on the right front wheel well that has a crimped pin. Second try we replaced the brake control module for $680 and it died twice on the way home. To date it’s only died while driving surface streets @ 20-40 mph. The only alert is “service steering Column”

What we try next is anyone’s guess. Any ideas?

 

[Tylerldurden]

It

Has this happened more than once?

I would consider replacing the FPCM (Fuel Pump Control Module), these are known to do some crazy things other than hard fail. About $65 and you can easily replace it. Some of the 2021 models may have had a recall for the FPCM as I recall.

s happening at irregular intervals and the techs at GM haven’t been able to replicate with the diagnostic computer hooked up while driving. It happens on surface streets @ 20-35 mph only, to date. The only other weird alert is “service steering column lock” which comes on all the time.

 

[Tylerldurden]

So this is a bit of a spitball as there is not a lot to go on here. Assuming you have checked for codes with an OBDII tool and/or a more advanced tool just to see if there are any clues and you found nothing, then this is my take.

If there are no clues and it was my truck, knowing what I know about the FPCM issue and for under $65 and the ease to replace it, I would get a new FPCM, swap it in and see what happens. It may or may not resolve the problem, but here are some things to consider:

1. I have not had a chance to dig down and see what a more advance scan tool can see with regard to the low pressure fuel system. I doubt the FPCM had the smarts to indicate an intermittent fault and I am not sure there is a low pressure fuel sensor.

2. The FPCM are known problems, they often hard fail, however, I have seen instances where they fail intermittently. A bad solder joint that over heats or is subject to issue with low ambient temperature would not likely be easy to find and could cause the problem you are having.

3. Even if the FPCM is not your problem, there are 2 good outcomes here:
a. You have eliminated the FPCM as a problem so you and or the dealer/repair shop can focus on other areas if the problem persists.
b. You then have a spare, backup, FPCM for when the operational one actually fails and leaves you stranded.
c. You can always sell the spare FPCM module and recoup most or all of your money if you choose not to keep a spare in the truck.
d. If the replacement FPCM solves your problem and it would have been a warranty repair, then you could submit for reimbursement for the part and/or labor if you had a shop swap the module. Effectively you are out nothing in this instance,

See this link here for more info on the FPCM part number and some sources - https://www.tahoeyukonforum.com/threads/spare-fpcm-fuel-pump-control-module-wise-idea.152090/

While you may be covered under warranty, for the $65 or less the FPCM costs and the easy of replacement, to me it is not worth even dropping such an intermittent problem off at the dealer for repair as they likely will not duplicate the problem and you will be having the same problem and discussion months from now. Changing just 1 variable that is somewhat of a known problem would be a great way to eliminate the FCPM or possibly solve your problem.

Good luck.

Thank you very much. We’ll try this next.

 

[Tylerldurden]

The o

Misrouted harness and subsequent wear. Look it up in recalls. In particular look near the alternator bracket. Do you ever get weird dashboard messages regarding brakes and cruise control and collision avoidance system? Should get some codes, but if the ECM has a power interruption, maybe not.

The only consistent dash alert is “service steering column lock”.

So far we’ve fixed a faulty ground pin and swapped the brake module for $680. It was GM advanced service tech’s best guess but it hasn’t solved the random stalling.

 

[jfoj]

Not sure I have much of a solution, however, a quick search on the "Service Steering Column Lock" message indicates that there may be a problem tied to the anti theft system. So the question is there something triggering the anti theft system and shutting down the engine??

If this is tried to the anti theft system and there is an error, it may be shutting the low pressure lift fuel pump causing the engine to shut down.

Many owners with this error had disconnected the battery to clear the error, it would usually stay away for a while.

I would do a lot of research on how the anti theft system operates, how the keyfob is detected and see if you can get any additional clues as to what may be causing the "Service Steering Column Lock" message. I have not checked to see if these newer push button start vehicles actually have a steering column lock or if the electric power steering is just inhibited. The engine may also shut down because if there is something that thinks there is a problem with the steering column lock, then the engine may shut down so as to not have a loss of directional control while driving??

If the vehicle has the original battery, I would consider replacing it just for good measure as well. These vehicle also use an adaptive charging system or as system sometimes referred to as Smart Charge which will actually shut off the alternator under specific conditions. If the battery is questionable, when the alternator is shut off, it could cause some strange behaviors with some modules.

Good luck.

 

[dbphillips]

The o

The only consistent dash alert is “service steering column lock”.

So far we’ve fixed a faulty ground pin and swapped the brake module for $680. It was GM advanced service tech’s best guess but it hasn’t solved the random stalling.

That was one of my codes. I'll check the invoice later and see if they call out the tsb.

 

[dbphillips]

That was one of my codes. I'll check the invoice later and see if they call out the tsb.

https://static.nhtsa.gov/odi/tsbs/2023/MC-10232712-0001.pdf