2021 Yukon Electrical Issues

[Farrengui]

Hey Guys, I’m new to the forum and I am having issues with my 2021 Yukon Denali, 

I am getting the following Codes: 

 

• U0211, U0214, U0247 → lost communication with modules (seat, door, etc.)
• U0186 → lost comm with infotainment / HMI
• U1962 / U452 / U230 / U1132 → network configuration / gateway faults
• B13AA, B178C → body/seat-related faults

and here is a printout from GMC 

I am thinking it could be a faulty ground or one of the modules, I had the BCM, SDGM and radio module reprogrammed. the issue is that the seats don’t work, Backup camera doesn’t work, trunk won’t open. GMC wants to change each module to see if that helps and that is EXPENSIVE. If I could get some insight of things to check before I jump out there and dump a lot of money into it. I would be greatly appreciative. 

20260426030946199498.pdf

[CaptPat51]

Did this ever get solved?   I'm chasing 2021 Yukon Denali electrical issues - vehicle will not enter sleep mode - we can disconnect and reconnect the battery and it will sleep - but that's likely because we powered down whatever module doesn't correctly sleep.  once we start/accessory the vehicle and turn off, it will stay at 11.5 amp draw with something keeping the SDGM alive - it appears to be activity on the X2 segment, specifically CAN FD Bus 5 - but we don't know which device and we think we've already isolated all of the devices on that segment - so what keeps the BCM and/or the SDGM alive is unknown.   I don't yet have a packet trace from CAN 5 (and since this Global B we might not get much info from it) - but the vehicle has been down for 8 weeks and previously GMC Dealer was unable to resolve "kills battery" issues with this particular vehicle - so I'm at a loss - it seems to be beyond local repair capabilities - and the number of "telematics keeps vehicle from sleeping" posts indicates this whole architecture has major issues - I hate to say it, but we might have to install a battery cutoff switch on the front grill - one of those red boat switches - to turn off the vehicle.;)  Any pointers appreciated;)  I just bought a CAN FD interface and I'm planning to try Savvycan and Peak Can SW to triage this further.

[CaptPat51]

BTW, the 11.5amp draw is all the usual systems active - it's not a single draw - that's the "we're all awake" state of the vehicle - forinstance if the power steps are actuated, the draw will spike to 22amps for that operation.  when the battery is disconnected and then reconnected, the vehicle shuts down that one time only - and we see a 10-15minute progression down 11.5  10.5  9. 8 6. 5. 1.6... 500ma... and then off to sleep at 40 milliamp... as expected.  So we know it's a module that is simply refusing to allow the SDGM to proceed to the sleep state.  We do NOT think it is the telematics VIM module - since we already duplicated the problem with the "VIM bypass" solution installed (we reverted that since it also disables the gmc app - but it does not appear that the telematics system is the culprit).  We've replaced the rear heater control module, tested without the wireless charger, and the other modules on CAN Bus 5 - but still something is keeping us awake and removing X2 from SDGM allows sleep to proceed.  We cannot diagnose from OBD since OBD drops off at about the 9volt level in sleep mode and we can't communicate with the vehicle - also we can't trace the SDGM internal packets from the OBD side - we have Autel Ultra.   Any ideas on why disconnecting X2 would allow sleep to proceed appreciated.  This is no longer a repair situation - this vehicie is simply unusable in this condition and NOBODY at GMC Dealer can even understand what it is doing.  This is crazy.  We made these systems too complex and now we're paying the price.

[CaptPat51]

We tested the sleep mode with an ammeter in series with the negative battery terminal - 30amp fused - so we do know the actual shutdown and non-shutdown current draws and timing of the shutdown sequence.  We just have no protocol information to determine what module is issuing the (likely) network management (NM) keep alive.

 

Edited 19 hours ago by CaptPat51