Is it possible during the replacement of the Accessory Power Module https://static.nhtsa.gov/odi/tsbs/20...81063-0335.pdf that the dealer accidentally deprogrammed the Serial Data Gateway Bus? That is the code that comes up, but I don't get any symptoms besides the 'Service Hybrid System" message on the DTC.

 

I just came across something that may be related to my issue. Would appreciate some expert analysis. My 2013 Yukon use to have a great ride, even mentioned by my Uber passengers. I don't drive Uber anymore, but now it seems the ride is really harsh on small bumps and expansion joints when slow, but great on new pavement. I just read that the magnetic ride system goes through the Serial Data Gateway Module. Is it possible because that module, according to the dealer service department, is the cause for the Service Hybrid System message that it is causing a rough ride? If so can I temporarily bypass the system to see if the ride improves? This has rear air-ride so I am not sure if the rear struts are magnetic also. Ride leveling works when loaded so shocks aren't leaking. Seems the roughness is from the front. I read somewhere to add a spacer on the ride height sensor on the front to fool the computer to soften the magnetic system in the front. Anyone have any insight?

 

Ok, I finally got to the GMC dealer in Grapevine, TX to have the Accessory Module replaced under the extended warranty. Yes no charge thanks lvflyer for the info. They then cleared all the codes. Yet the Service Hybrid System still came on, but NO other codes are thrown. If you remember it was coming on about every 20-30 minutes. Now it only comes on at start and like lvflyer, once I clear it with the button, it never comes back until I turn the Yukon off and restart. The dealer tech spent 5 hours on it and on the phone with others techs he knows have worked on Hybrids elsewhere in the country. The only code showing is b-1000 in the Serial Data Gateway Bus and he said that code has NOTHING to do with the Hybrid System and that he has confirmed that with 2 other techs. They did offer to try and get a Serial Gateway Bus, I said hold off on that. My Yukon Denali did come with magnetic ride and rear air adjust. I had the front shocks replaced with Arnott replacements and Magnaride bypass plugs to trick the system to think the magnarides are still there and new factory rear air shocks. The codes did not change their pattern at that time so probably no correlation.

Where the dealer and I left it. Go and and see if anything else happens and they will keep researching. In the 2 weeks nothing has happened other than daily turning off the Service notice and it stays gone until restart with my reader no codes as well.

The Dealer also asked if I had a brand new battery because it trends on all their meters as a brand new battery. So great confirmation to S Keith's evaluation method of my battery readings a year ago.

Will update if I get any changes or the dealer comes up with something. Otherwise I will go forward pushing a reset button every start up.

 

Sounds identical to mine. At least I have backup now, I'm not crazy. I think it is a residual code that is not cleared in normal way. What happened to all the 2-mode engineers? GMC won't even try to analyze it for me since I don't want to pay a tech to spin their wheels. Let me know if the research turns up anything. Dealer here wanted $1500 to install a SDGB. I would think there would be other symptoms. What I have discovered is the SDGB is the same on all GM SUVs and maybe trucks. Problem is if I get a salvaged one the dealer won't program for my vehicle.

 

I was having the same message for a while once it started getting cold. No other issues. I also saw the service bulletin but I think it was for a different code. The dealership replaced the serial gateway data module 3 days ago and I haven’t gotten the service hybrid message yet. My truck was only there for 2 days so apparently the part isn’t that hard to come by. Gm actually called me to replace my airbags as for the recall. The dealership told me they can save me $100 since they already had it open. Apparently the SGDM is next to the airbag. Ended up costing me $300. The airbag was covered by GM.

 

Daniel, do you have information on the airbag recall? Wondering if mine is in a recall. Paul

 

i don’t. GM just randomly called me a couple weeks ago. You can prob find something on google, call up GM or the dealership though. Mine is a 2011. I’m guessing they’re all the same

 

Thanks Daniel. I should have just checked my vin on the GM Recall sight instead of asking. It came to mind moments after I hit reply.
Since I gained the knowledge I might as well share it -

To check to see if your 2007-2013 Yukon, Tahoe or Escalade or (any GM vehicle) has any recalls including air bags go here and put in your VIN number https://my.gm.com/recalls

You can also go here to check any auto manufacturer for recalls by VIN
https://www.nhtsa.gov/recalls

 

omg ive had this message for over a year now. Finally took it to the dealer and they said they need to replace the serial data gateway module. Stating that the SDGM i have is bad and therefore cannot have communication to be reprogrammed. The dealers that do have it will not sell it to the dealer where my car is at. So my dealer has contacted GM to contact those dealers to try to convince them to sell to my dealer. So replacing this module fixed the service hybrid system message? Also did anyone have success by putting in a used unit without having it reprogrammed? Trying to fix this so i can sell the vehicle. Although this msg has no problems, it will definitely scare away any car buyers.

 

mine hasn't had this problem yet but from reading thru this thread, replacing that module seems to fix it.

​​​​​​if it was me, I'd look for a used one, install it and if it worked sweet, if not, I'd go to the dealer and ask them to flash the modual with the latest software. probably cost and hour labor. I wouldn't bring up that I changed it out or anything. just tell them you want that specific module programed with the latest gm software.

hopeful you get it sorted. seems like some successful posts in this thread. the issues seem to be finding the module for some reason or the dealership just being a hassle to work with. you can find local shops that can program modules after replacing them too. it's just a service they have to pay for monthly from gm to access. so you'll have to find one that does enough of that kinda work for it to be worth while to pay for the service. there's also some very long threads about what it takes to program modules yourself as well. 200$ tool, a older laptop, fiddle with the software downloads and pay gm 65$ I think it was for 45day access? something like that if you wanted to go down that rabbit hole the info is out there.