GM_Tech

Have you had the code pulled from the BCM, TCM, PCM..???

If you have a C0327 code you can fix it by removing the encoder motor and replacing the encoder motor sensor inside (as opposed to spending $300+ on a new encoder motor).....It's a very common problem. If there are no codes or a selector switch malfunction code, you'll need a new selector switch assembly. Neither is a big deal or very expensive. Especially if you D.I.Y.

The only other possability is if your front differential is making a groaning noise on decelleration, you may have bad bearing races and excessive play in the yolk assm, causing the front axle indicator switch to trip within the differentail itself. this one will be costly and labor intensive to fix...Not a do it yourself for the average back yard mechanic.

Good luck...keep us posted on what you find.

meatball

Got my truck back the Dealer changed the computer module, as of now they tell me all electrical parts have been changed.Waiting for it to act up again. There was no code on any of the problems.

pipefittermn455

i have a 06 chev silv. 1500 with a sevice 4 wheel drive light that comes on. when it comes on i can not get the truck to go in to 4wd or the light will come on as soon as i start it and all the lights on the push butten 4wd are not illuminated and will do nothing. had a prob with the wiring harnes geting all mesed up from falling down and hitting the drive shaft but it was fixed and now this is happening any one know where to start??????

Michael J.

I had same problem with Service 4Wd in 2004 HD. Changed fluid (Red ATF) and problem has gone away. Had approx 50,000 mi on old fluid. Very simple to change.

s34n

could be the actuator in the t-case. my 4wd message came on while in the dealer. dealer changed out the actuator and no problems since. that happened in january 2009.

landiman

I have a 2000 Chevy Silverado 1500 LS with a 5.3 Engine. I have the Service 4WD Light come on intermittently. I have had advice and I have read everything here. Sometimes it works fine. Other times the Service 4WD light is on and there are no lights on the switch panel.
I watched a video and changed the switch panel with a new one from Chevy, they are $110. It was the same. Intermittant.
Then I changed the Transfer Case Control Module which is $200 from Dorman and is located behind the left airvent/switch cluster in the dash in a VERY inaccessible area. I tested it before I put it in and everything worked. Reassembled the dash and it was the same, intermittent and annoying.
As a co-incidence, I have recently changed all the oils in all the axles, tranny, engine, power steering with exactly what they should have. The next thing is the actual engaging actuator on the front axle, the motor that engages the front axle. When the light is off and it is working, I hear and feel the reassuring clunk of the 2WD and 4WD and Hi/Lo working. This tells me that replacing this $600 unit is a waste of time and money and the issue is electrical. If it is electrical, what else is there to check with the new TCCM and dash switches?
Thanks

David Kostyla

I had the same problem. My truck is for sale, an idiot came over to test drive it and figured he was somewhat capable of transfer case knowledge as he had a truck already.. Well, he goes ahead and throws it into 4low while driving on pavement and wouldn't ya know, it failed.

Idiot. "Service 4wd" message displayed on dash, all related 4wd indicator lights gone. To make a long story short, I did some research here on the forum and wanted to try the easiest troubleshooting first versus going crazy and purchasing a new transfer case..

If you have the same problem as mentioned above.. I was able to fix mine easily. Try this first:

Find the fuse (located in the side dash fuse panel), pull the 15amp fuse for 4x4. Mine was intact. I waited 3-4 minutes, replaced the fuse and restarted the truck. That alone fixed it. Try it first on your vehicle if you encounter the same problem. Hope it helps

landiman

How do I know which fuse it is?

David Kostyla

Landiman;

I've added a few pictures for the location of the fuse. I have a 2001 silverado and a 2004 duramax. Although each fuse is located approximately in the same spot in the fuse panel, I've included pictures of each. Both 4wd fuse locations are in the driver's side side dash fuse panel. Pull the fuse, check it for integrity, wait a minute or two, then replace the fuse. Mine sort of "rebooted" the system I guess and everything works as normal now. Hope it solves the problem for you.

Best;

Dave


2004 Duramax 4wd fuse location schematic, drivers side dash panel (yellow circled)



2004 Duramax 4wd fuse location in fuse box (yellow circled)



2001 5.3L silverado 4wd fuse location schematic, drivers side dash panel (yellow circled)



2001 5.3L silverado 4wd fuse location in fuse box (yellow circled)

landiman

Thank you very much.