Just returned home from 2 days in Daytona Beach with my '03 H2. Spent maybe 20 minute of "wheel turning" on the sand. (hard pack) When I got up on the highway the DIC showed a "service 4wd" message. This is the first time in 145000 miles that I've seen this. I "erased" the message and drove home (225 miles) with no problem and no message. I stopped for gas and when I restarted the car the message re-appeared but it still drives OK. Is "4wd service" a specific action or is it another opportunity for the dealer to get into my wallet ???? I've had this H2 since it had 9000 miles and NEVER had this before..........Thanks

 

Tough to diagnose without scanning it. Could be a few problems. I'd have it scanned first then at least you will have a general idea of the problem. have you been changing the fluid in the transfer case regularly? have you been running four matching tires on your hummer always? is the trans case fluid burnt? any leaks?

 

maybe it's time for a fluid change. Does the 4wheel drive work? or does it feel only half?

 

I had the same problem with my 04 - it turned out to be a sender unit on the transfer case

 

H2 has been sitting for about 2 weeks. Changed the shocks, outer tie rods and did the the front brakes. Started the truck to take it to have the rear brakes done and the DIC message SERVICE 4WD came up. Didn't seem to be any problems. I scanned it today and no codes (KOEO). But tried to start and no go batt low.
Remembered about some fuse that the service manual mentioned and went to check it. What I found was mice have been crapping in my fuse panel in the engine bay and chewing on the wiring harness that comes out the bottom of the panel enclosure! So now I have to clean and mend the harness AND track down this fault. Wife's gonna be super P.O.'d that her trip might be delayed even more than waiting 'til Fri. to get a new windshield (combo heat & hail).
QUESTION: Does the H2 have a CAN network or can I use my regular OBD2 scanner to check things out?
MikeH

 

Well, took apart most of the connectors around and under the fuse block in the engine bay.....found more chewed wiring.......and one dead mouse! Don't know if it got trapped under the connector that it was nibbling on, OR it bit into something it couldn't handle.
What a Royal PITA!
MikeH

 

The H2 does have a CAN network, not sure how that bit of knowledge will help you here though.

 

Hey Pauldy,
It just means that I need to spend some more $ to have that programming unlocked on my scanner!
MikeH