Hello, Everyone-
New member here and first time posting. I am the new owner of a 2003 Hummer H2. I am very happy to own it but I have been having some problems and wanted to see if anyone could provide some recommendations where to start looking. I got a really good deal on the H2 and went over it pretty well beforehand. Everything checked out fine other than an issue with the shifting. Here are the symptoms: When placed in N and pressing the 4hi button, I hear the actuator start working and the light on the 4hi button stays lit indicating no issues. When I shift into D, it seems as if the tranny isn't engaging. Same with R. Eventually, going from N and placing into D, I will get it to engage and I can drive for maybe 100 yards and it seems the tranny will then pop out of gear and be in N. So to remedy this at this point as I have not driven it far before I get this issue resolved, I will go ahead and put it in N and place it in 4hi lock position. Every gear works in this position. When I initially press the 4hi lock button, I can hear the actuator moving but it will continue making a movement noise until I place the H2 into R or D and then it will stop and go into gear. The only odd noise I hear from the 4hi lock position is when placed in R, upon driving a few feet backwards, I will feel and hear a loud "clunk." Doesn't seem to affect anything but also is not a noise I would expect to hear. My first thought is U-Joints so I already plan to change those soon, anyways. I like to do maintenance on any vehicle I get so I have already done oil change, both front and rear differential fluid changed with Lucas 75w90, and transfer case fluid change done with DEX III. None of the fluids or drain plugs had any alarming metal shavings in or on them. Tranny oil checks out nicely as well but I will be doing a tranny fluid/filter change soon as well. I have researched already and some issues were the actuator itself so I have one on order and will install it this weekend. I also intend on checking the bushing that breaks on the shift cable but I don't believe this would cause the transfer case to not be able to fully engage while in 4hi. I prefer not to tear into the transfer case but I do understand it could possibly be the poorly designed plastic shift fork as well, but I would figure it would have issues shifting in any gear if that were the case. Please let me know if anybody can think of anything else they might believe I am overlooking. I greatly appreciate the assistance.

 

there are 2 neutrals. one is the usual one for the transmission the other is for the transfer case to disengage it from the transmission for towing purposes. if you look at the 4 wheel drive selector, you will see it shown to press the top and bottom buttons together until transfer case neutral light illuminates.

 

I'm tracking the 2 different neutrals. I didn’t believe this to be the case as it will, on occasion, go into gear in the 4hi position if I fiddle with it for some time, but after moving forward in D for maybe 100 yards, it will go out of gear and slip back in what seems to be neutral. It will shift fine in all gears if it is in 4hi lock or 4low.

 

is the 4 x 4 neutral light on when that happens? small yellow light.
could be the encoder motor needs to be cycled a bit or cleaned. same for the 4 x 4 switch. worst case then would be a failed shift fork or transfer case.

 

no neutral light indicator, only a solid yellow in 4hi. I’m replacing the encoder motor tomorrow either way in hopes this solves the issue but if not, I’ll have to tear down the transfer case and see what’s happening.

 

Buy an OEM encoder motor, the Dorman parts are usually junk.