Our 2019 Yukon Denali XL has had a parasitic drain that we didn't notice until it got cold and we ended up with a dead battery. We got it back in May/June of 2025, at that time I noticed that the battery gauge on the dash showed the battery was being charged at about 15v.
I didn't think much of it at the time because it fell in the highlighted area on the gauge, but then we had a dead battery in Dec 2025. We initially thought it was just a bad battery, changed out the battery and the battery gauge hovered right at 14v. We had another dead battery, I thought maybe it was the sharkfin antenna, which had a leak or our rear wiper motor, which was going bad. I finally got around to changing out those parts and it didn't fully fix the draw. I did find a couple of things that are drawings power, but I'm not sure how to fully diagnose the issue.
Dash activation video
Battery amp draw video
With the truck fully asleep, I found that something in/on the abs module would activate every 1 minute 35 seconds, I could hear it click. I pulled the fuse for that and the draw dropped a little, then I noticed that on the same time increment the instrument cluster and radio screens would wake up as well. I say wake up because screens would just light up the background of the screen, none of the icons or gauges would appear.
Another thing I did find out, from a GM tech, is that the Seat Memory Control Module (SMCM) could be waking up a low speed LAN bus when temps are below 40F, see doc below. The only fix is to replace the module.
I don't understand the LAN bus stuff at all. I also don't know if these modules are tied to the other two issues that I noticed happening.
Anyone have any insight on a similar battery drain?
Searchable text from photo:
Document ID: 6074038
Condition:
Some customers may comment on the following conditions when the ambient temperature is below 40 degrees F:
• Dead battery/required jump start.
• Slow crank
• Battery low state of charge, and if equipped, Auto Start/Stop inoperative
• IPC backlighting turning on intermittently while the vehicle should be asleep
• Keyless or passive entry/start inoperative
These concerns are not easily duplicated in the service bay or with temperatures above 40 degrees F.
Note: The condition is intermittent and ONLY occurs when the vehicle has been outside overnight or longer and the ambient air temperature is below 40F for extended periods of time.
Cause:
These conditions may be due to a low battery state of charge that is being caused by one or more modules waking up the Low Speed GM LAN Bus. It has been found that the Seat Memory Control Module (SMCM) could inadvertently wake up the Low Speed GM LAN Bus when the ambient air temperature is below 40 degrees F. This condition could apply to all SMCM a vehicle is equipped with like: Driver K40, Passenger K40P, Left Rear K40LR and/or Right Rear K40RR.
Note: Some vehicles without memory seats still could have a SMCM to control a Safety Alert Seat RPO HS1, example vehicle 2021 GMC Acadia.
I didn't think much of it at the time because it fell in the highlighted area on the gauge, but then we had a dead battery in Dec 2025. We initially thought it was just a bad battery, changed out the battery and the battery gauge hovered right at 14v. We had another dead battery, I thought maybe it was the sharkfin antenna, which had a leak or our rear wiper motor, which was going bad. I finally got around to changing out those parts and it didn't fully fix the draw. I did find a couple of things that are drawings power, but I'm not sure how to fully diagnose the issue.
Dash activation video
Battery amp draw video
With the truck fully asleep, I found that something in/on the abs module would activate every 1 minute 35 seconds, I could hear it click. I pulled the fuse for that and the draw dropped a little, then I noticed that on the same time increment the instrument cluster and radio screens would wake up as well. I say wake up because screens would just light up the background of the screen, none of the icons or gauges would appear.
Another thing I did find out, from a GM tech, is that the Seat Memory Control Module (SMCM) could be waking up a low speed LAN bus when temps are below 40F, see doc below. The only fix is to replace the module.
I don't understand the LAN bus stuff at all. I also don't know if these modules are tied to the other two issues that I noticed happening.
Anyone have any insight on a similar battery drain?
Searchable text from photo:
Document ID: 6074038
Condition:
Some customers may comment on the following conditions when the ambient temperature is below 40 degrees F:
• Dead battery/required jump start.
• Slow crank
• Battery low state of charge, and if equipped, Auto Start/Stop inoperative
• IPC backlighting turning on intermittently while the vehicle should be asleep
• Keyless or passive entry/start inoperative
These concerns are not easily duplicated in the service bay or with temperatures above 40 degrees F.
Note: The condition is intermittent and ONLY occurs when the vehicle has been outside overnight or longer and the ambient air temperature is below 40F for extended periods of time.
Cause:
These conditions may be due to a low battery state of charge that is being caused by one or more modules waking up the Low Speed GM LAN Bus. It has been found that the Seat Memory Control Module (SMCM) could inadvertently wake up the Low Speed GM LAN Bus when the ambient air temperature is below 40 degrees F. This condition could apply to all SMCM a vehicle is equipped with like: Driver K40, Passenger K40P, Left Rear K40LR and/or Right Rear K40RR.
Note: Some vehicles without memory seats still could have a SMCM to control a Safety Alert Seat RPO HS1, example vehicle 2021 GMC Acadia.
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