Service 4WD Light

[josephcmc]

My 4WD seems to be working just fine (it snowed this morning), but when I switch from Auto 4WD to 2WD the "Service 4WD" light comes on. Does this have any kind of reset like the "Change Engine Oil" message has? Thanks!

[GMCTech]

If the "Service 4WD" light is coming on then you have a fault in the system.

There is no "reset" and you'll have to get it checked for codes to see what it is doing.

Hope this helps.

[bsparks]

I had a similar problem on a 1999 GMC Sierra 4WD. The "Service 4WD Light" would come on intermittently (esp. after hitting a bump) and sometimes it would have trouble going into 4WD or back into 2WD. I also noticed that when "Service 4WD Light" came on, the lites on the 4WD switches were all off. I found the problem was cracked solder joints in the switch assembly. Pull the switch assembly out of dash, remove back cover and check solder joints of the the pins (approx. 5 -10) sticking through the printed wiring board. I reflowed the solder joints and it fixed the problem.

[budmanl98]

I had the 'Service 4WD" message show up twice on my 03 Yukon. Both times it happened, the lites for the 4WD module were off.

The dealer had to replace two modules to get it fixed. The sad part was, after the first instance, the service advisor said it would probably happen again and they'd have to replace another module. Of course, a few weeks later the "Service 4WD" message came up.