"Service 4WD" plus burning smell?

[devilsfan]

New problem - my "Service 4WD" keeps coming up. I've been able to clear it in the past by changing into high/low gear for a moment, but this time it keeps coming back on - but only after I've run the truck for a while, never on start up. Once I shut the truck off after running it, I've been noticing a burning smell from the front end, like meltiing plastic. Ideas?

[[__--MUD--__]]

Didn't you put headers on this summer? If so, i'd look to see if anything is touching them now.

[devilsfan]

Nope, headers are in the clear. I did see one of the wires to the headlights touching the engine though and resecured that. But on the way home today, it was more of a brake-pad smell and super strong. There was supposedly an industrial fire in that area tho, I hope that was all it was and nothing new!

[Ken Bowers]

I also have the "service 4WD" alarm after driving awhile. I received a hint that it may be due to low battery voltage, so I am going to do a full charge tonight. I will report later.

I have no ideas about the smell.

[guruerror]

The one and only time I got the Service 4WD it ended up being a faulty transfer case shift control switch (15127829).

15 in the diagram: http://parts.nalleygmc.com/showAssembly.aspx?ukey_assembly=392529&ukey_make=1027&ukey_model=14605&modelYear=2005

[devilsfan]

Smell is gone now, that's a good thing.

Been watching for my error message - it's very intermittent, and when the "Service 4WD" comes on, the locker button (top round button) starts flashing. Then the message goes off and the light stops. This will do this maybe every 10-15 mins when I'm driving, and lasts for maybe a minute.

[Hellz]

check the fluids in the T case?

[HummerJim]

The one and only time I got the Service 4WD it ended up being a faulty transfer case shift control switch (15127829).

15 in the diagram: http://parts.nalleygmc.com/showAssembly.aspx?ukey_assembly=392529&ukey_make=1027&ukey_model=14605&modelYear=2005
+1
Had the exact same issue when the H2 was new. It would come on randomly and then go off, but it started staying on and Lynch replaced the switch in 2007 and not a single SERVICE4WD since then. Problem solved.

[H2Much]

I've had this too. Can't remember it if was a switch or a sensor, but it was one of the two. Same thing as the other guys, when I had it replaced, the light never came on again.

[devilsfan]

Never came up all day yesterday. Odd.

Is this the $700 switch that needs to be replaced? If that's the case, I'll just deal with the blinking light.

[guruerror]

Never came up all day yesterday. Odd.

Is this the $700 switch that needs to be replaced? If that's the case, I'll just deal with the blinking light.
I think mine was about $75...I installed it myself to save the hour labor in taking the console and dash apart.