Service 4wd

Macken0310 · October 30, 2017

So, yesterday afternoon, I jump in my tuck after running errands. service notice flashes says "service 4wd" I dis miss this, check my 4wd knob and its in AWD, where it stays unless I need 4wd. I go to back up and turn and its clear Im in 4wd. Cannot get it out of 4wd. Tried running through 2wd/4hi/4lo etc. nothing no shifting at all. I drive a lot so my truck is at about 54K (its a 2015, bought in 2015) and I have had no issue with it so far. great truck. no complaints. So, I drive into town today, call the dealership (who at first said they couldn't look at it till Tues- wed) they eventually say they can squeeze me in today around 2. Great! I think this is great. Still under warranty, if it has to be messed up better now then in 6k more miles right!- but wait. looking up their warranty the most likely culprits (wiring, tccm etc) aren't covered under warranty. Really. with so many others having this problem?... I can accelerate and drive it, turns are irritating. Seeing that there aren't any real "fixes" for this since 2014 not a good start to this week. Anyone find anything that seems to have stopped this action from reoccurring?

diyer2 · October 30, 2017

I wouldn't run it in AWD all the time.

2WD would be my choice.

joshc64311 · October 30, 2017

4 hours ago, Macken0310 said:

So, yesterday afternoon, I jump in my tuck after running errands. service notice flashes says "service 4wd" I dis miss this, check my 4wd knob and its in AWD, where it stays unless I need 4wd. I go to back up and turn and its clear Im in 4wd. Cannot get it out of 4wd. Tried running through 2wd/4hi/4lo etc. nothing no shifting at all. I drive a lot so my truck is at about 54K (its a 2015, bought in 2015) and I have had no issue with it so far. great truck. no complaints. So, I drive into town today, call the dealership (who at first said they couldn't look at it till Tues- wed) they eventually say they can squeeze me in today around 2. Great! I think this is great. Still under warranty, if it has to be messed up better now then in 6k more miles right!- but wait. looking up their warranty the most likely culprits (wiring, tccm etc) aren't covered under warranty. Really. with so many others having this problem?... I can accelerate and drive it, turns are irritating. Seeing that there aren't any real "fixes" for this since 2014 not a good start to this week. Anyone find anything that seems to have stopped this action from reoccurring?

Let me know what you find out

Macken0310 · October 31, 2017

Scan showed c0398 code- transfer case control module- tsb outlines that if you have a c0398 code you've probably also had/have c0392 and c0396 codes, i believe. That might not always be the case. They checked for updates and cleared the code. They did cover it under warranty and it's currently in 2wd and working normally, however, I haven't tried switching between 2wd/4wd and I've left it in 2wd instead of awd. (Other post say to leave it in 2wd unless 4wd is needed then be sure to switch back to 2wd before turning truck off-so im trying that logic). This fixes it today, but isn't signed off as a permanent fix by dealer.

Mr. Z71 · October 31, 2017

When DTC C0398 sets, the vehicle is permanently locked in 4HI and cannot be shifted out of it while the code is present. This is a software problem. The fix is a software update. Had my 2015 updated and no more problems. It is service update 28770.

See this...

https://gm.oemdtc.com/7291/28770-service-update-4wd-ips-drift-dtc-c0398-4hi-lock-up-2015-2016-cadillac-chevrolet-gmc

Edited October 31, 2017 by Mr. Z71
remove duplicate wording

NickyNorker · September 28, 2018

I have a 2015 Silverado 1500 and just had to deal with the "service 4wd." It seems that driving in "auto" for more than 1.5 hrs can cause this issue. We had a terrible rain storm a few days ago and I was stuck in traffic for 2hrs with the "auto" selection on. I didn't realize there was an issue until I tried turning into my driveway, it felt like I was in 4wd. After reading numerous posts I tried everything, disconnecting the battery, pulling the 30amp 4wd trec fuse... and nothing worked. I took it to the dealer and they had to reprogram the TCCM. 2 codes came up: C0398 and U0403. I got tagged $130 for the diagnostic fee but that included the reprogramming. I hate having to go the dealer but didn't have any other choice and I'm out of warranty so I ate it. Going forward, I was told to avoid this issue again, don't drive for more than an hour in "auto" and when you are shutting the truck off put it back in 2wd.. hope this helps

Gator567 · November 6, 2023

I have the same problem with my 2016 Sierra . I watched a u-tube video on how to reset the computer & clear the 4x4 service light . I followed the instructions & got it working ! Of course I didn't write down the procedure & now I can't find the video ! Now that I see what issues other people are having ; I can see where I'm going wrong . Apparently you MUST shift to 2 wheel drive BEFORE you shut the truck off !! Talk about stupidity !! If & when I get this system reset I will definitely pay attention ! Thank you for all the great info !

Anthonywar · September 29

On 10/30/2017 at 6:51 PM, joshc64311 said:

2015 Silverado 1500 5.3 4x4 service light. In the power link box I pulled the fuse number 6 I heard the transfer case engage and put it back in and it reengaged but it fixed the service 4wheel drive not sure how long it will be fixed but I was able to take it from 4h to 2wd. Might help someone

Edited September 29 by Anthonywar