"Service 4WD" - Master Thread

[jeff ashworth]

I have a 1999 Tahoe and the transfer case or front end wont lock in it does nothing, replaced the push button switch in dash, shift motor on T case, actuator on front diff., still nothing, when I pull the fuse out of the fuse panel and put it back in it sounds like the transfer case control module behind the light switch is making a noise could that box also be bad.

 

[kiwi]

Update on my 4wd service message.
It turned out that i have faulty switching knob. Basically it's a potentiometer, and different voltage settings change modes.
My voltage in 2wd mode is somehow flawed and is changing periodically. So it caused service messages and auto shifting.
Will be replaced for free, 40 days wait time to ship new part to my dealer, lol.
They said its the first time ever they meet this knob faulty

 

[Keith Turcotte]

I’m new to this forum;

I have had my 2015 Tahoe new and have never had a 4WD problem until recently associated with a variety of other electrical issues that recently came up.

Basically the needles on the control console keep moving for no reason associated with service air bag; service parking assist; service “front camera”; service traction control; service hazard warning system;

Anyways while trying to also figure out why my brake pedal and interior lights were connected I was moving the 4WD switch around to try and see if anything was related and now I have “service 4WD” alarm message and I’m pretty sure the vehicle is stuck in 4 wheel drive Low.

Also the ignition now intermittently doesn’t start; no idea why and two weeks before I can get it into the dealer.

There must be a pretty big electrical ground somewhere?

Anyone figure out the transmission issues?
Anyone have the same electrical issues?

I believe there is a service bulletin I just read about changing the interior lights to solve the brake light flash issue.

Any help or advice I’m a DIY that usually breaks everything three times first before finally making a repair.


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[bigrhino]

I have a 2011 Tahoe and the service 4wd message came on. 99% of the time I'm in 2 wheel drive. If I'm in a foot of snow or more, I use the 4wd to free the Tahoe out of the snow.

 

[SpineDock]

2015 Tahoe LT still shows ‘Service 4 wheel drive’ randomly but she has never gotten stuck in 4WD.
Fingers crossed!!

Should I ask dealership to do the update on the TCM or let a sleeping dog lie?!!?!

 

[Aggie76]

Wife had the "service 4WD" show up this evening as she started up and backed out of garage. She pushed the "reset" check mark and said it went away but didn't tell me about till after we left it at tire dealer to switch from winter to summer tires first thing tomorrow.

We've got about 128k miles on our '15 Yukon XL Denali and have never had issues using 2HI, Auto or 4HI during our long winters here in northern MN. Had a decent winter storm on Thursday night that resulted in "no travel advised through NE North Dakota. But had to get to somewhere on Friday morning for medical procedure that couldn't be postponed so we drove in 4HI on the completely ice and packed snow covered I-29 interstate at 45-55 mph to the hospital. Had a few moments of "oh no" but got there in one piece. Not for faint of heart with semi's and others flying by at 70 mph at times.

Weather cleared on Saturday and switched back to 2WD as roads were dry. Noticed a bit of noise from the rear end but it went away during our trip back home, about 150 miles. Then the message showed up this evening as I mentioned above.

Will see if the message is still there in the morning when I go back to the tire dealer with the summer tires to be installed. And I'll check to see if what drive mode its in as well since she couldn't recall.

UPDATE: Error message stayed on so got appointment with local Chevy dealer. Got it into them on Wednesday and quickly decided to reprogram the Transfer Case Control Module and that has taken care of the problem at this point.

 

[jaxscuby]

recently during afternoon down pours I stopped, selected park, changed to auto from 2H and expected the 4x4 light to come one. it did not, so selected 4H
still no 4x4 light. turned back to 2H and continued on my way.

and now the "service 4wd" notification..oh joy..

2016 Tahoe LTZ 5.3 / 6L80

where is this encoder motor?