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: 121,471 (18,400–220,000)
Drive Trains affected: 2WD, 4WD
121 people reported this problem
Tahoe. No lights on 4wd push buttons, service 4wd in display, both fuses good. No 4wd. just happened so not fixed yet.
Drive train jumps from 2 hi to neutral and sometime 4 hi and 4 low. This never happen while driven. Only when you start the vehicle up, you must check the selection.
my service 4 wheel drive indicater is showing on my screen what is the fix for this
My 4 wheel drive dont work, the light on the selector is solid on on button but flashes on another, Ive replaced the selector switch and the 4 wheel drive actuator but has not helped.
I had the same problem with the 4 wheel drive transfer acting crazy. Took it to my Chevy dealer and they started exchanging parts with no idea to the problem. It took 4 trips to the dealer until they gave up. It cost me over a grand and I demanded them to fix my truck. I did some research on the internet and found TSB #05-04-21-003C dated Apr. 15, 2008. It instructed the Tech to check the wiring harness from the encoder to the sensor. The wiring harness will short out from moisture and cause false reading to the sensors. I hand delivered this TSB to the Chevy Service Dept and told them to check the wiring harness before they replaced the encoder. I finally got my truck back at 4:00 PM working great. You know and I know, they will never admit to what really took place. So guys check your wiring harness before you start pulling sensors, when your transfer start acting crazy.
When in 2wd while driving will jump into neutral can put in 4wd auto and drives good
Grinding noise when attempting to use 4WD. Indicator lamp turned yellow and occasionally red.
Similar problem, switch fail, but now it's even worse. had my actuator replaced, and the thing went into 4 low by itself then neautral, now only runs but wont move in any gear.
sometimes it works ; electric shift, sometimes it doesn't. seems to be affected by slush and cold. sometimes the red neutral light goes on, sometimes the whole thing goes blank. Once I was driving the red neutral light was on and all of a sudden it whacks down into 4 low. Luckily I was just coming ouut of town and not up to speed. When spring hits and I can look at it,I can't get it to do it. Never fixed third winter coming up now.It is getting cold now and it is starting already, red neutral light on. start up truck is in 4x4 without ever selecting it.
Won't switch back to 2wd..
I had "service 4wd" message come on an it would go away until I restart truck. There were no diagnostic codes stored anywhere. I did buy 4wd encoder switch and was going to replace it but did not. What I did find is cold solder joints in my 4wd switch on dashboard, the cold solder was not detectable with bear eye I had to use magnifying glass. In any case before you go spend money on encoder switch, take your 4wd switch from dashboard apart and solder all pins of main connector on that board.
I had the exact intermittent problem on start up. I took mine to an honest and reliable transmission shop (Terry's Transmission in Syracuse, NY) after I had replaced the selector switch. They determined that it was in the wiring between the selector switch and the encoder motor. They said the encoder was fine. They referred me to a good electric shop, but I did not take it there for the electric repair yet. Likely it is a corroded connection that is "helped" by damper weather since there seems to be at least some correlation with the weather.
Will not work on 4 hi or 4 low. But Will engage on 4 auto can not figure out the problem
The vehicle will transfer into 4wd with out being selected.
All the lights in the switch work, but it will not shift from 2wd to any other position. when the button is pushed the light blinks and nothing happens. The TIC displays "service 4wd". I found info on the net about a bad ground and how to clean it. I disconnected the ground, sanded the connection point and reattached it. this fixed the problem for about two weeks, then it stopped working again. Removed the ground again and took a grinder to the attachment point. This worked again for only a week to 10 days. very frustrating.
stuck in 4wd auto looking for solution finally took it to a dealer (sorry floks they got you over a barrel the modual shorts out and they have to reprogram it) no they dont carry parts on hand no you cant do it yourself
Vehicle randomly switches in and out of 4wd
Lights on switch will not come on .changed switch and cleaned the ground wires
4W Service message appeared intermittently and would reset after pressing milage button. Re-appear sometimes after minutes and sometimes days..Dealer found the sensor to be bad and replaced $300.
Removed xfer case encoder motor after removing plate and pulled front drive. Manually put into 2wd w/drive socket wrench and drove for 5 days before affording part and repair. Total cost under $300.00 including $60.00 for installation by area mechanic.
Got most of my info via internet and local Public Library. Ask yours about ENSCO, and you may be able to access Chilton's repair manuels.