2014 Sierra slt “service 4wd” message

[2014 GMC]

While driving in slippery conditions selected 4wd auto mode, as per procedure, no issues. Parked truck with auto mode selected. When next started got message “service 4wd”.

Selector light on at auto mode. Attempted to select 2wd, no go, attempted 4wd hi, no go. In both cases the indicator light did not blink as would be expected, as a matter of fact there was no indicator light showing either blinking or otherwise. When returned to auto mode indicator light was on and I was able to drive the vehicle with out any problem and I believe it is  still in auto mode. Any suggestions or ideas as to how I can get it to shift back to 2wd. 

[Bash74]

Take it in and have them check it. This could be it, who knows

Recall 15304
4wd always engaged in cold temp
Expires with base warranty
Updated calibration
Transfer case shift control module reprogramming with SPS 9101695.

In low ambient temperatures, below 5°F (-15°C) a transfer case brake motor assembly malfunction may occur. Diagnostic Trouble Code (C0398 - Range Position Correlation Fault) will be set, locking the transfer case in “4HI” until the vehicle is serviced.

Sent from my SM-G935V using Tapatalk

[2014 GMC]

Bash74, thanks for the info. I plan to make an app today. I was thinking that it maybe just a software “freeze up” that I may be able to sort out at home as the service centre is 100 mile away and they are usually busy which could mean waiting a week or more for an appointment, to say nothing of the costs involved!!

[aseibel]

so when you drive right now, are the front wheels engaged or not? 4auto is basically 2wd unless the rear wheels are slipping. i would just put the knob in 2wd for now.

 

unless you are in need of 4wd to get anywhere. I think some more experimenting is needed to verify what your truck is trying to do right now. Can you drive fine if you put it in 2wd? shifting from 4 auto to 2wd isn't really noticeable.

[2014 GMC]

Andy, thanks for the interest. I believe the front wheels are engaged ie the auto mode maybe selected but infact it acts as if its in 4hi. No issues with driving even with 2wd or 4wd hi selected (though there is no indication light for 2wd or 4wd hi, only light that displays is in auto )  

Spoke with the dealer and he says its stuck in 4wd and that it needs to go on the comp. 

I was wondering if someone knows how to restart the stuck software?? Obviously the dealer will not pass on a easy fix!!

[aseibel]

I think you can reset the computer by disconnecting the battery cables for a half hour. Then touch the two cables together before hooking everything back up.

 

But I don't know that would fix the 4wd actuator if it is stuck.

 

My reason for asking about the front wheels is if you can drive it for a week or longer until getting into a dealer to look at it. If your wheels don't bind and hop when turning, then you can keep driving it as normal. But if it really is locked in 4 HI and you are on dry pavement, you are going to have difficulty turning corners, and causing wear on your tires and the whole 4WD system. If that is the case you need to get it looked at ASAP.

 

If you are actually experiencing the cold weather issue, (I had my software updated for that same bulletin Bash74 posted) I would recommend finding somewhere warm to park for a few hours and then see if it will operate as it should again.

[2014 GMC]

Andy, thanks again. I'll try the battery disconnect though I'm wondering if touching the cable together prior to reconnecting will harm the comp?

fully understand the potential consequences of driving with 4wd engaged, thanks for the heads up.

i had the truck in a heated garage overnite and condition still the same so I believe it's software issue.

[aseibel]

Yeah, that's why I said I don't recommend that battery method, I've never done it. I've just heard that's how its done. I suggest you google it to learn more. I think you only touch the ends together to make sure there is no current left in the system since capacitors can hold a charge for a while. I don't think it harms anything if you have left it sit disconnected a while first.

 

You may call your dealer's service dept first and ask if they think that would solve your problem.

[rlbock]

My 14 did the same and the front was in 4 wheel, which you will know as soon as you turn on dry pavement going slow. Mine needed the update and it has been fine ever since. When going slow and turning on dry pavement is when you will notice the fronts binding more so than driving fast.

[2014 GMC]

Andy/Bob;

Thanks, right now I’ve the battery disconnected - will let you know how that goes. Meanwhile booked in the truck for tomorrow. 

[2014 GMC]

No success with battery disconnect method. Wasn’t brave enough to touch +/- cables together !!! metered across cables and got a reading of 280 mV, so I decided that discretion was the better part of valour!!

Will update again after I get finished with the dealer’s shop.

 

[Mogly]

2014sierra 4wd stuck can't get out of 4wdrive all dealers will say is bring it in so we can charge you for diagnostic out of warranty, has only 24000 miles on it. Dec 11 , 2017 front ball joint drivers side pulled out of control arm. Said was part of warranty ended up paying 936.00 for repairs haven't got towing bill yet.  Could have been killed if happened on interstate at 65 miles per hour. Dealer claimed never saw this befor, said I must have hit something . I never hit anything. Found numerice complaints  online same issues. GMC has our money and won't back up their junk cars.

[2014 GMC]

Back from the dealers shop, surprisingly is was very painless!! To quote the W/O “ Check for service 4x4 on in dash.

Checked for codes, found CO398, checked for current update. All O.K

Replaced actuator position sensor, relearned, and cleared code"

This was covered under extended warranty, parts and labour.

kilometers 68,762 (eh)

milage 42,704

Still have a long way to go to get back the ext warranty value though.

 

thanks for all you help

[Megs]

Update: it was my battery that caused the issue!!! Just happy because that’s a lot cheaper fix than the actuator!!! 
 

Just out of curiosity how did this all pan out for you? My 2014 did the same exact thing back in March 2019, took it in and they replaced the actuator, then today November 2019 it went out again! I live in MI so cold weather is a big deal this time of year! I really am curious on the update thing as they did not do that last March and would like to know a little bit about what I am talking about when I call the dealer tomorrow after they have looked at the truck! I’m a women so unfortunately they talk down to me like I don’t know what I am talking about so it would be nice to better educated when I speak to them! When I told them it was the actuator again they gave me a stupid look and an uh huh, I’d take it elsewhere but unfortunately the other dealer is backed up two weeks! Any help and advice is greatly appreciated! Thanks in advance! 

Edited November 19, 2019 by Megs