I was in the middle of installing a new head unit in my H3 when I realized I needed to pick up make a run to the nearest auto parts store for some more parts/relay. So, I started the hummer without plugging/re-installing in the dash /radio console cover (i.e. 4wd control unit/ a/c heater controls, emergency flasher switch). Immediately the "Service 4wd" light starts flashing. This had me concerned so I plugged the cable back into the switch and restarted the engine. The 4wd status looks normal (4H), but the warning light is still on.

I'm planning to remove the negative battery cable today to see if it clears the code, then see if it comes back on after I put everything back together.

Anyone else have this problem? Sure would hate to have to go to the dealer to reset it.

-Tim

 

computers ,plural,monitor and control EVERYTHING in the veh but the radio station,well maybe that too. so you really kinda should normalise the control systems b4 running it.
i dont think it will notice if ure dome lite is out!!

 

Push and hold in the odometer reset button and the code should go away.

 

I had the same issue happen when I installed radios a couple of times in my earlier H3's, it always cleared itself after a bit of driving. Shouldn't be a problem.

 

Thanks for the replies. It seems to have gone away for now.

After I finished installing everything, I disconnected the (-) battery cable and stepped on the brake pedal, pressed horn a few times to make sure all power was drained . After starting it back up, the a/c controls did a diagnostic test, and the Service 4WD message seems to be gone also. Hopefully that's the last I will see of that message. :-)

BTW. I installed the Pioneer AppRadio and a relay to bypass the parking brake.
AppRadio | Pioneer Electronics USA

Now I need to order a good backup camera to hook up to it.

-Tim

 

thanks for posting

 

Lets see some pics, been shopping for the last couple months before i buy. Want a touch screen with pandora, and hd i pod cable (that i dont need to purchase extra)

 

https://www.hummerforums.com/forum/h...-camera-26061/