My 2017 eco will do a very similar thing. Very violent lost of power then immediately pick back up. The EVIC shows something about low battery voltage. Power saver mode. Only happens when the ambient temps are below freezing and engine is not yet up to temp. Also happens very infrequently. May...
I believe its located behind the drivers side knee bolster (lower edge of dash). I think a couple bolts on the lower edge then snap pins to remove.
Wayne
Sean,
I just repaired this fault on my 17 ecodiesel, here's what I found.
The trouble shooting SOP mentioned above is spot on.
Check fuse 31 for continunity
if good check pin 11 on the plug for the heater control module, found on the cross member above the drive shaft near the transfer case...
If it says 80 percent and has not gone into limp (limited power )mode then there are a few other parameters that must be met to go into regeneration. Engine must be above (i believe) 170 degrees f and rpm must be 1500 or greater for at least 1 minute. Then rpm can not drop below 1500 for more...
Finally retired the 2004 GMC and replaced it with a Ram. So Far I'm very pleased with the switch, ask again in 10 years.
Lots of good information here so let the transformation begin.