4 wheel drive off

[FisherMatt]

Hello all.  New to the forum and I appreciate any help. So I’m climbing a 10% grade, well maintained dirt road that’s covered in packed snow the other day and suddenly I get the warning ding and a message that says 4 wheel drive off. Rear end breaks loose, traction control stops the climb, and I’m stuck. Truck off and on a couple times, will start shift into 4 wheel drive then does the same thing. Had to chain up to get out. Owners manual says this will happen when the 4 wheel drive system is overheating. I had used it for about 2 minutes and nothing was more than warm to the touch. Can’t find anything online about it. I have no idea where to go from here without going to the dealership and spending all that cash! Any help is much appreciated. 2014 Sierra 1500 Crew, 4.3L 6, 98k. 

[swathdiver]

There should be an internal code to look up.  Need bi-directional scan tool like these: https://www.obdadvisor.com/gm-scan-tool-review/

[FisherMatt]

Doesn’t show any codes. 

[300 Blackout]

Tag. Can’t offer any help but I’m interested to hear what you find.

[FisherMatt]

Still can’t figure anything out. Going to change all fluids and double check any connections. Message comes up on dash screen and goes away once acknowledged. Doesn’t come in again unless key is cycled. Any ideas? I’ll update after trans case and diffs fluid changes. 

[Rukus]

Are you in 4hi/lo or Auto?

[FisherMatt]

Been happening in 4 hi consistently. I’ve had it happen in auto too. 

[FisherMatt]

Changed all the fluids. Pretty dark all the way around. Definitely needed changed. Ran it in auto for about 20 miles and all was good. Here we are 3 days later and finally got some snow. Put it in 4 hi just to see. Worked great until I left a red light and started to slip a little. Traction control kicked in and 4 wheel drive off. I shut the truck off, turned TC off, and tried again. Won’t even shift into 4. Looking more and more like a trip to the dealership. This thing has worked fine for years. Only thing I’ve done lately was change shocks and struts. Can’t think of anything there that would cause this. Only thing I disconnected was the abs sensors. Could one of these be the issue? Don’t have any abs warning lights or anything. So frustrating. May be cancelling my first ice fishing trip to the mountains on Monday. 

[Z45]

Do you mean to imply the ABS sensors are permanently disconnected?    Some one doing the work may have messed something up.

[300 Blackout]

I’m sorry to hear about the ongoing issue. I really have no idea what could be causing this. My only guess is if you somehow shorted something out when disconnecting/reconnecting the ABS sensor. I really don’t know. Keep us posted.

[silveradosid]

have you checked the electrical connector for the transmission there was a tsb for loose wires that would cause the tcm to lose communication

[FisherMatt]

ABS sensors are both reconnected as normal. I’ll disconnect, inspect, and possibly replace today. I guess I could have nicked, pulled, or smashed one somehow in the strut process. I’ll also check that transmission connection. Thanks for all the responses and I will update later today. 

[papageoff]

Sub'd.

[FisherMatt]

Disconnected and reconnected the abs sensors. I get warnings like I should when they’re diconnected, none when connected. Bought a scanner and it doesn’t even throw codes when the message is active on the dash. Just made an appointment with the dealer for after Thanksgiving. I’ll update after they diagnose. 

[FisherMatt]

So...it’s been a battle. Dealer discovered that one of the front diff bearings had come apart and run through the diff trashing it. Whole front diff had to be replaced to the tune of $2300. Fought with them for about 15 days over warranty coverage. I was at 100400 miles and about 45 days past my 5 years. Finally ended up paying $990. They covered the rest. Truck works great. Dealing with most of these guys is like beating your head against the wall. Had to just keep at it till the manager went to bat for me. In the end it turned out good.