U0403 TSB?

CaptainCanuck · January 8, 2015

Haven't seen this anywhere in the forum, so figured I would post my experience in case someone has the same problem.

Left work yesterday after the truck had been sitting for about 8 hours in -40 C temp, plugged in of course. Got about 100 ft when the service 4wd message came on and the selector switch was stuck in auto. Asked on star to run a diagnostic and got a U0403 message. Brought it to the dealert next day and they reset the TCCM.

Service tech showed me a bulletin from gm where they know the TCCM gets stuck in cold weather, and a software update is in the works. Till then he advised me that I could very well see the problem again. Apparently they had a few trucks in that day with the same problem.

Funny thing is I live 2 mins from the GM cold weather test facility.. but hey, -40 Temps aren't a laughing matter, even my park sensors had a fit, was just glad it started.

Drive safe.

bdbake01 · January 8, 2015

Dude...move! Holy frozen nuggets batman!

CaptainCanuck · January 8, 2015

LOL. Its not so bad today, a balmy -24c; atleast i can breath outside.

Service tech called me back today after doing some more research on this problem and gm advised putting the truck into 2wd when parked. Apparently the tccm will only code on start up in auto/4wd.

Drive safe.

krellheat · January 8, 2015

look here. http://www.gm-trucks.com/forums/topic/162543-service-4wd-message/page-4?do=findComment&comment=1554664

AZGMCZ71Leveled · January 9, 2015

Don't have that problem here in Arizona. It's 75 degrees today.

Blizzard721 · January 14, 2015

I have the same problem. My dealer has no idea what to do. They are saying we have to wait for GM engineering department to find a fix. I thought they tested these in the cold. It's -25C here and now I'm with a truck that is either stuck in 2 wheel drive or 4 wheel drive but no option to change it! This is ridiculous!!!!

GMC-AT · January 15, 2015

why do you guys live in that stuff... it's 55 here today and I feel like I'm going to die.

Blizzard721 · January 15, 2015

Seriously. ..winter is great most times. I love snowmobiling, skiing, and everything to do with fresh air and being outdoors! I can't imagine living where there's no winter! That being said when it does drop to -20 or 30....it's too cold...but it doesn't last forever! And I make a fortune working here! Now....if I can get my truck to work in the cold I'd be happy!

Blizzard721 · January 20, 2015

My 2014 is stuck in 4 hi and has been reprogrammed to no avail. It has a code C0398 and GM is saying the cold is the issue! Seriously???? Now I drive around in 4 wheel drive all the time destroying my front end on dry pavement and getting horrible gas mileage! But hey...a fix may come some day when the weather warms up! I guess I bought a summer model!

Blizzard721 · January 27, 2015

Any word on a fix yet? Been a month for mine now! They're saying if your trucj was built before September then this problem is likely to happen in extreme cold so what's the difference when built after September? ?? Software or hardware???

SILVER SLED · January 27, 2015

There is a bulletin for shutting the vehicle of in anything but 2wd when below freezing. If you do shut it off in 4wd when below freezing, the transfer case will get stay in 4wd. Usually when this happens, the 4wd knob will not light up on certion settings. The dealership should be able to clear the codes set and get everything back to normal. However, it could still happen again if shut off in 4wd when below freezing. GM doesn't have a fix for it yet. So until then, shut your truck off in 2wd.

So, has the dealership tried just clearing the codes.

Blizzard721 · January 27, 2015

Yes they cleared the codes twice and told me about the 2wd shutdown but after a few days of short haul trips where I needed 4wd it was shut off in 4wd and coded and locked up again on startup! They'll wait till spring and the problem will fix itself. ...until next winter and we'll start this over again! Are all these trucks doing this??? If not, what's the difference. ...software or hardware???

SILVER SLED · January 27, 2015

Alot of them are. Take it back and have the codes cleared again.

JS03818 · January 28, 2015

Hey guys new to the site and i was reading this and was finding this very odd due to my truck having 4x4 issues also but only coming out of a 70 deg heated garage not extream cold. ill turn it to 4 high back out of the garage and the light will not light up, minutes will go by an it might go 10% of the time. the rest i got to mess with the switch. been flashed once already did nothing, having radio, bluetooth issues too. been at the shop more than ive had it!!! well good luck with the fixes..