Service 4wd light

[eyzonly]

The Service 4wd light on my 03 Silverado 2500HD came on and none of the 4wd buttons work and the little lights don't light up. I replaced the switch with a new one and it still doesn't work. It's like there is no power to the 4wd switch. I checked the fuses and they are fine. Any ideas on what the problem could be?

Thanks.

[madmatt]

Leave the fuse out for a few minutes and try again. The module is staying in sleep mode and not waking up. If it happens again there is a reprogram to correct this and in some cases, the Transfer case module will have to be replaced.

[eyzonly]

Thanks for the reply. Where is this transfer case module located?

[jbplock]

There was a common problem with the 03's caused by a faulty motor encoder in the transfer case ... had it happen on my 03 ...

At first I would get an occasional service 4WD drive message in the DIC that would clear. But after a while the 4WD buttons started acting strange indicating it was in 4WD when it wasn't.

see this thread .. also do search on "service 4wd" or "encoder"

http://www.thedieselpageforums.com/tdpforum/showthread.php?t=16788&highlight=encoder&page=2

You could pull the 4WD fuse to make sure the transfer case doesn't get stuck in 4WD ...

[madmatt]

#02-04-21-006E: Inoperative 4WD/AWD Lamps, Inoperative 4WD/AWD System, DTC C0550 Set No Communication with TCCM (Reprogram Transfer Case Control Module) - (Jul 20, 2006)
Here's the one I'm talking about. Also the one I've seen the most

[ToddMeister]

Had a similar problem on our 2002 Trailblazer, replaced with a used Transfer Case Control Module out of a wrecked 2003 TB, problem solved.

If replaced with a new TCCM, it will have to be programmed with a Tech2. New ones have no programming.

[eyzonly]

Thanks for all the info. I removed the fuse for about a minute and replaced it, and all is fine now. I guess I'll have to get the tccm programmed with the latest software. Hopefully that's not too expensive.

[madmatt]

glad it worked. the reprogram shouldn't be too much. I think we charge $40.