Service 4WD Light

Pancake0341 · February 17, 2020

Having the issue with the service message coming up in snow storms (WI) on my 2019 chevy 1500, they did a relearn on the transfer case and it didn't fix the issue. The dealer said they've had replacing the tccm fix it, but the most common issue is snow and ice building up around the sensor housing and once it heats up around the trans and transfer case, the ice melts with debris and trips the sensor. So, they've cleaned and resealed a few housings and that fixed their issues on a few. We'll see if that's what they do for me this time with mine, it's the second appointment I've had and I've made sure to take pictures of each instance of the code going off, so they can't tell me there's nothing wrong.

Jay P · February 17, 2020

4 hours ago, Pancake0341 said:

Having the issue with the service message coming up in snow storms (WI) on my 2019 chevy 1500, they did a relearn on the transfer case and it didn't fix the issue. The dealer said they've had replacing the tccm fix it, but the most common issue is snow and ice building up around the sensor housing and once it heats up around the trans and transfer case, the ice melts with debris and trips the sensor. So, they've cleaned and resealed a few housings and that fixed their issues on a few. We'll see if that's what they do for me this time with mine, it's the second appointment I've had and I've made sure to take pictures of each instance of the code going off, so they can't tell me there's nothing wrong.

Do you know which sensor?

Pancake0341 · February 17, 2020

2 minutes ago, Jay P said:

Do you know which sensor?

I'm not sure, they weren't very specific, I just got back from the appointment and he showed me a list about 200 pages long of gm updates they were sending out literally every other day for the tccm and transmission. They recently stopped on this new one because they claim it fixed the problem, it's supposed to snow about 4-6" tonight, so I should have a chance to check if it worked...

Jay P · February 18, 2020

I agree with the sensor theory. I only have issues when there is a lot of road spay from the melting snow and temps below 25. Once I get up to highway speed the problem clears and the 4wd indicator goes back to white and the service 4wd goes out so ice buildup makes sense.

Jay

JTC14 · February 21, 2020

I brought my 2019 Sierra in for service at 8000km and to check why the Service 4wd light kept coming on. Dealership ran diagnostics and said the 4wd module needed to be replaced. The truck has been in the shop since December 16th, I keep being told that the part is still being manufactured. I am beyond frustrated with GM at this point. I expect some serious reimbursement from GM to rectify this wait

brianf60 · February 21, 2020

Makes you wish we had a lemon law in Canada too doesn't it?

Colossus · February 21, 2020

17 hours ago, JTC14 said:

I brought my 2019 Sierra in for service at 8000km and to check why the Service 4wd light kept coming on. Dealership ran diagnostics and said the 4wd module needed to be replaced. The truck has been in the shop since December 16th, I keep being told that the part is still being manufactured. I am beyond frustrated with GM at this point. I expect some serious reimbursement from GM to rectify this wait

you won't get any. Don't ever get your expectations up.

JTC14 · February 22, 2020

Picked it up today, 67 days later! Hopefully issue is resolved. GM is working on adding the 67 days back onto my warranty. Fingers crossed

Tymick13 · February 24, 2020

Dangit! It’s claimed another member. Happened to me today. Took the 2019 AT4 into a bad snow storm and after letting it sit outside for 5 hours. The E brake was on and so was the service 4WD light. After getting it home and into the garage. The light went off and after reading this thread I highly doubt it’s going to stay off. Thanks for the good info everyone.

Denali Driver · February 24, 2020

Hi Folks, Glad to hear this issue with "service 4WD" is not isolated to my 2019 Sierra Denali 1500. I First experienced it shortly after 3000Kms in wet snowy muddy highway conditions while in 4WD auto mode. The auto mode went from white to amber color and when i stopped the vehicle the E-Brake automatically applied. After driving on into better highway conditions the auto indicator light color, service 4WD light and E Brake all corrected itself. This has happen multple times since and i now have 12000 kms on the vehicle. I still haven't informed my dealer about this issue.

The other issue is with "rabbits" apparently they love to chew on my block heater cord. I've had to shorten that cord a couple of times and wrap it with duct tape.

Good luck everyone.

Dan V 25 · February 27, 2020

Truck is going in tomorrow to replace the TCCM. Dont think it will fix it but heres to hoping

Jay P · February 27, 2020

The only time I have an issue is when it's snowing and the roads are sloppy/slushy. It has something to do with ice coating or hanging on something. As soon as I get up to highway speed (stuff warms up) or all the stuff melts out from under the truck the issue is gone and the 4wd light is back to normal color. Unless the TCCM is somewhere it can get ice on it thats not the problem.

Jay

Edited February 27, 2020 by Jay P

hatchet669 · February 28, 2020

I wonder if i'm starting to get the beginning of this problem. Other day i get out of the truck and i hear a bunch of whirring sounds. Sounded like transfer case motor. Next day the little icon on the dash that says 2WD was missing. Turned it off and on a couple times and it eventually came back on. This has happened a few times now, but no service 4wheel drive light yet. Did anyone notice anythign similar before?