Suburban Transfer Case Disengages While in 2WD

sab03

My 2006 Suburban transfer case will randomly disengage while in 2WD mode (happens 2-3x per week).

Instances of when this has occured are:
- Driving on interstate at 75mph
- Driving around town at various speeds
- While in reverse it is initially engaged but will slip out
- shifting from Drive to Reverse

What happens to vehicle when it occurs
- Transfer case appears as if it's in neutral as vehicle will roll.
- Light on transfer case control stays lit in 2WD mode
- When shifting vehicle to park will make a grinding type noise. Will put vehicle back into gear and have same problem of no engagement (engine just revs). I have also tried turning vehicle on/off while in this condition and it still does not correct.

What I do to correct:
- I push either the 2WD or Auto 4WD button and transfer case re-engages. I can then put the vehicle back into 2WD and it will drive fine until the next time it disengages. I may be noticing a decrease in mileage, but at this point can not say for sure that this is occuring.

Again, this issue only occurs while transfer case is in 2WD mode. I have taken the vehicle to the dealer and they replaced some gears?? in the transfer case, but I don't feel that they have a good grasp of the problem. Any help/guidance you could provide would be appreciated. Thanks

ngfinch

I had the same problem in my Tahoe. It ended up costing me $1600.00. The fork that engages the front differential got mis-aligned some how and wasn't sliding in betwee the gears like it should and ended up grinding them down. So sometimes it would go in sometimes it wouldn't. The only time it worked for sure was when it was in 4x4. Good luck!

todd77

I had the exact same thing happen to me yesterday on my '05 Chevy Tahoe while driving on the freeway at 70. The symptoms you describe are exactly what happened to me, only after the 3rd time I was unable to get the transfer case to re-engage. What did they end up finding wrong and what did it set you back? I'm expecting a diagnosis and estimate tomorrow morning. I have just under 50K miles on the car. How many miles did you have?
Thanks,
Todd

ekspat

I realize this an old post...but did anyone get this problem resolved?

woodycox

need an update on your problem/solution!! Help!!! Having same prob.

rhtrans

I realise this is an old post but this answer may help someone in the future. Their are two things that can cause this, like one of the other posts...a bad low range fork in side the transfer case can cause this, which is usually caused by low fluid level damaging it thru lack of lube. If the fluid is full and fairly clean, the most common reason is the encoder motor position sensor. The motor is bolted on the side of the transfer case. The position sensor is inside the encoder motor. The sensor tells the PCM what position the forks are in by using feedback voltage. What happens is the sensor will start giving the PCM wrong voltage readings...the PCM then begins to rotate the motor until it sees the voltage it wants to see, but the Pcm does not really know the position of the forks inside, so if your buttons on the dash say 2WD mode it wants to see a 2.98 voltage feedback...so if sensor is bad it may actually be in neutral when it obtains that voltage reading. The sensors are available thru the dealer without buying a new motor and fairly easy to change. Used to have to buy a whole motor but GM finally came out with a repair within the last year. A scanner helps to dianose this problem and no, it will not always set a trouble code. Hope that helped

wayward_burb

This post was immensely helpful. I just bought an '05 Suburban on 29 November with 137K on the clock. Test drive went well, mechanic ok'd it a couple days before purchase - the morning after I bought it this happened, and twice more on the 700 mile trip I had set out on. Has happened twice more since then in the past 3 days. Again, thanks for the post.