Problem Description and Possible Solution
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.
Average mileage: 132,135 (15,900–323,000)
Drive Train affected: 4WD
11 model years affected: 1990
, more1999, 2000, 2001, 2002, 2003, 2004, 2005
62 people reported this problem
I can not get my truck to go into 2 wheel drive at all. It switches between 4 high and Low on its own.
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.
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.
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
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.
4wd kicks in on its own. sometimes it kicks into 4 lo, sometimes 4 high. so far it will shift out when i hit the 2wd selector button. but i have been told that it will eventually lock into 4wd.
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
Initial problem was front axle engage/lockup when inappropriate, temporarily mitigated by choosing 2 wheel drive instead of auto 4 wheel. Next problem occurring a few months later was random mode selection absent of any human assistance and most commonly between auto 4 wheel, 4 wheel hi and 2 wheel. This problem progressed to No indicator light on mode selector switch beyond initial all lights test with ignition as well as no mechanical function of the 4 wheel portion of the drive train.
Being the highly experienced and proficient mechanic that I am, I used my Acton OBDII Plus reader and retrieved the codes frequently described in this and similar forums. Most common of these codes is C0327. The shorter explanation is that I have replaced both the selector switch itself as well as the transfer case encoder motor. I achieved a single instance of switch indicating 2 wheel mode upon completion of repair. When I chose another mode, the switch went dark and no mechanical activity occurred. That is the issue that remains now. My next guess would be to replace the TCCM but I would like to trouble shoot it first as I absolutely hate being a parts replacer instead of good mechanic that truely diagnoses the problem and fixes it.
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.
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!
the suburban with shift into 4 low automatically while driving
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.
switch will not change out of 2w drive, no lights or error codes
Yep, same problem. I Noticed crazy sounds on the front end of my truck, and after replacing tires, wheel bearings and inner and outer tie rods, nothing changed. Took it to a Goodyear nearby and they asked me to switch to 2WD...well what do you know? NO sounds...drives fine, BUT the darn thing keeps switching back and forth from 2WD to 4WD Lo and Hi, and every now and then the display says Service 4WD, so for now I'm driving in 2WD...will be getting it serviced AGAIN next week!! Love my truck, but not the issues it's having.
I have Chevy suburban 2002 I put the 4x4 I used it in the snow when I went to put it in 4x2 I press all the button and it stood in neutral also where u press the 4x4button don't show that is let ...
I don't know if it's the switch on the dash or the sensor on the t-case. Sometimes it switches by itself upon start-up and/or it won't switch out of the drive it is in. Very frustrating GM.
no indication of drive high low 4x4 or 4x2 upon start up begin to drive in neutral when she decided to switch into 4x4 low and 2 high at 70 mph .i was entering a construction zone when i dropped it down to 45 and she ended up shifting to 4 low there was no shoulder and was on dry pavement!now she is grounded until i am able to afford to fix her.i drive my 95 wrangler 5 speed with 19700 ,original motor trans and 2ond clutch now....what a pathetic joke gm
6 kids 2 dogs and 1 wife ....
great job Chevy real safe...
Indicator lights work but does not work and does not go into 4wd
There's always been a roaring sound in transfer case since new. 4wd encoder failed about 70000 miles and blew transmission. Replaced both. 2 yrs later the same thing happened. Replaced again. Now, two yrs later, encoder is out again. Light says 2wd but car is actually in 4wd and stuck. This should have been recalled. If I ever get rid of it, I'll never have another chevrolet.