Bruce Alsup

Try free service at https://www.carcomplaints.com/

I had the same problem with my 2009 GMC Sierra 3500 HD. Spent a month and $$$$ trying to get it right. First, the regen doesn't work properly if the glow plugs are not working. Have to replace those first, then try regen (or pay the GM garage $$$ to do it). Next, the 2008-2011 models before DEF are not able to regen sufficiently if you are pulling a load through mountains. Even with everything working properly. GM should have done a recall but got away with it. Only solution if you are going to haul loads in hilly terrain is DPF delete. You can also remove the DPF and have it cleaned commercially (about $800). This will work for awhile but only if you are NOT hauling a load.

General Motors produced several years of vehicles with a faulty transmission control module. From 2008 thru 2015, Chevrolet and GMC 2500 & 3500 trucks with the 6.6 L Duramax engine and Allison 1000 transmission all used the same TCM; part number 24256861. This part has experienced a very high failure rate. During the summer of 2022, the meager stock of replacement parts was exhausted and GM has not made plans to manufacture new parts. An estimated 5000 vehicles are currently unusable due to the failure of this part and no new parts available. It is our intent to file a class action law suit against both General Motors and Allison Transmission to have new parts manufactured. If you are interested in joining this class action, email to [email protected] with the phrase "GM/Allison Transmission Control Module Class Action Lawsuit" as the subject. Please comment on your experience with your 2008-2015 Chevrolet/GMC truck with the Duramax/Allison 1000 transmission. Join our group on facebook: https://www.facebook.com/groups/597481695185791

When you leave the truck idleing for a lengthy time, it will honk. Eventually it will turn itself off.