The 4WD transfer case encoder motor position sensor or the selector switch may fail causing the service 4WD message to be displayed. Fault code(s) stored in the transfer case control module will be of assistance in determining the exact fault causing the message to be displayed.Google+
Car Problem Reports
Chevrolet Suburban 2500 4WD Transfer Case Position Sensor/Selector Switch May Fail
Chevrolet Suburban 2500 Problem
Drive Train Affected: 4WD
Average Mileage: 124,195 mi (15,900 mi - 323,000 mi)
Visitor, 2004 Chevrolet Suburban 2500, 4WD, 77,000 mi
Transfer case gear selector not operating properly, replaced and continued to have problems, when I turn on vehicle I never know what drive I'm gonna be in. Sometimes 4low, which is the worst c opti . Try getting to work on the hiway in 4low, why isn't this a recall item, very dangerous.
Visitor, 2005 Chevrolet Suburban 2500, 4WD, 100,000 mi
I can not get my truck to go into 2 wheel drive at all. It switches between 4 high and Low on its own.
Visitor, 2005 Chevrolet Suburban 2500, 4WD, 84,500 mi
Service 4wd digital message appeared on my information center, is intermittent, two wheel drive seems to always work, but can not put it in 4wd when it appears.
Visitor, 2005 Chevrolet Suburban 2500, 4WD, 82,229 mi
Service 4 Wheel Drive Light came on. Took it to the Dealership for diagnostic. Dealer informed me at that time that the Encoder motor had failed. Replaced Encoder Motor back in May, 2008 for $1, 118.00. Recently my service 4 Wheel Drive light came back on. Took in to the dealership on September 2010. There diagnostic disclosed that the encoder motor has failed and the cost of repair would be approx. $800.00. GM need to do a better job at building a better product or they will never be successful in this current market place. This is totally unacceptable.
Visitor, 2003 Chevrolet Suburban 2500, 4WD, 82,000 mi
can not get 4 wheel high or low to engage 4x4 service lite comes on what sucks is the 4 wheel has only been used three times and it sounds like a lot of owners have had the same issue WHATS UP GENERAL MOTORS
Visitor, 1999 Chevrolet Suburban 2500, 4WD, 15,900 mi
My indicator light does not work all the time. I am not sure it stays in the correct mode. I don't want to replace the switch if that is not the problem.
Visitor, 2005 Chevrolet Suburban 2500, 4WD, 82,000 mi
The 4WD button does not work therefore leaving a message on the dashboard LED saying Service 4WD. Its so annoying, I just fixed this problem before winter started. I will never buy another Chevy again!
Visitor, 2005 Chevrolet Suburban 2500, 4WD, 160,000 mi
the suburban with shift into 4 low automatically while driving
Visitor, 2005 Chevrolet Suburban 2500, 4WD, 102,000 mi
Service 4-wheel drive warning erratic. Now when snow is 2 feet deep the lights on control panel go out completely. Unaable to to shift into 4 wheel drive. Grrrrr
Visitor, 1999 Chevrolet Suburban 2500, 4WD, 250,000 mi
On a logging road last Summer, pushed "4 Hi" button but nothing seemed to happen. When I tried the button again it was very hot. Not wanting to be stranded by a fire or other breakdown in the middle of nowhere, I left it in 2wd (at least, I assume that's what it was in) and drove home. Various internet threads offered many possible causes, but it was obviously a fairly common complaint. Yesterday, I pulled the fuses for the transfer case and 4wd (behind triangular panel at driver's end of dash), neither blown, but both having somewhat corroded legs. After cleaning, I re-installed them and everything works fine! Talk about a cheap fix! Makes some sense, though, as the corrosion would cause resistance, and at the same time keep some current from passing through the fuse, so the switch heats up and the fuse doesn't blow.