Hello all,

I’m not experienced in 4x4’s so I reach out to the community to help us sort this problem that we’re encountering, so please bear with me on the explanation of the symptoms (please take into account that I’ve never been a 4x4 owner)

Vehicle in question: 2002 H2 6,0L automatic

History:

- Rented and signs of potential hard running but before then (6 + months, running normal use and care before renting)

Possible cause of failure:

- diff was locked for some period of time, even in normal driving conditions possibly running in 4 HI for long periods of times (with the diff blocked??).
- heard that running 22” rims might have an influence over time (?? have to get the details better defined)

Problems encountered:

- We are experiencing a “locking” of “one of the rear wheels/both wheels” (doesn’t matter which one, i don’t think) , upon hard cornering from a a standstill, with throttle.
- feels as if the foot brake is applied from a stand still, but as well as from a rolling idle then applying gas. In general feels as if the P. brakes are applied.
- feels as if the foot brake is applied when reversing (even more so!).


Things that seem that are working:

- the election of the 4 wheel drives settings for 4 normal to 4 Hi to 4 Low are functioning from the **** pit so assume the selector buttons are working without problem
- audible functioning of the transfer case upon selection of the option(s) (didn’t note exactly when it happened, but noted functioning).
- the diff block works (only on 4 low, setting it in neutral)
- the diff block flashes on the rest of the settings (4 Hi and 4 Normal ,setting it in neutral while changing the settings)


Theories:

- there’s a probable parking brake issue (the best case scenario)
- Something has gone wrong in the diff. (input much appreciated!)
- the transfer case (although i figure less likely, due to the fact that the front does not experience problems) . I run on the theory, and I assume, that the transfer case governs the power distribution between FRONT and REAR but not between the "left/right FRONT" or "left/ right REAR" hand side…please correct me if I’m wrong.


Much appreciated input from all of you, thanking you all before hand!!!

 

I must add, that I've tried an OBD2 diagnosis but the hardware just wouldn't hook up. We checked the fuse under the hood ( cig lighter fuse) but the fuse was ok, non the less the hardware (unlike on several different applications) refused the give a green light where normally it would show a green light even if the bluetooth antenna didn't hook up with the app due to protocols.... once again any input is appreciated.

 

sounds like rear diff is locked in posi, I think you can only do this from 4lo mode though so it may not have unlocked if someone put it on, ive never used mine so I don't know if the button lights up etc when rear diff is locked in posi, ive had muscle cars with posi rear diffs and the rear wheels would chirp or grab sometimes if I was full turn from dead stop and was always told that's normall for posi, sooooo its seems like your rear diff is locked in.....also check the rear fluid make sure its not very low or gone or full of water etc I had a full size blazer that was making noise from rear end and was told to change the fluid and it actually cured it so maybe you get lucky

 

ps when its locked in posi both rear axles are spinning at same speed locked together that's why on hard turn one skips or grabs on dry ground, aalso don't know what exactly will happen with bad fluid as far as lubrication of clutches etc in rear diff but could possibly be the problem

 

Will look at that as a cause there yoymon, thanks for the insight, will put the theory on the table, test it out (fluids) and see what comes up!!!

The light flashes if we try to lock the diff in 4 normal or 4 high but activates (holds a light) in 4 low... maybe it's not releasing?

The engine fault light is on so I'm sure that we can possibly get a good hint through the obd2 but as mentioned I can't get my bluetooth wireless hardware to hook up with the ECU, so we're feeling our way around, right now, till we figure out why the obd2 is not responding or what we stumble upon along the way, what ever comes first.

 

correction (can't post edit right now)

"The light flashes if we try to lock the diff in 4 normal or 4 high but activates (holds a light) in 4 low, maybe it's not releasing... true! Will also put this on the table and have a look"

If anyone can suggest a (decent) downloadable shop manual, it would also be of great help!

 

I have an 05 and can only lock the rear when in 4Lo. Lights flash in 4Hi. According to the manual I have seen this is normal. Also to unlock sometimes it is required to run in reverse for 20 or 30 ft but that may only apply to the 4Lo.
You are correct that the transfer case only applies torque to the front and rear not the left or right. As stated previously check you fluid. Cant ever hurt to change it anyway. This will show if you have metal in the fluid which could mean bigger issues.
I am hoping all checks out and it turns out to be a P brake sticking issue. I never use mine except when parking on really steep inclines.

 

Resurrecting the thread.

We took the lid off the diff to see if we could find anything obvious but we didn't, oil was old but no signs of metal. Our obd2 scanner doesn't communicate although it shows power on the wireless antennae so we can't run through error codes, so, until I can get a proper 4x4 mechanic around (easier said then done where we are here in Spain) we need to try to feel our way around the issue. (I found it odd that the OBD2 connector on the vehicle only has 4 wires running into it ...is it normal?) The truck is up in the air, rear wheels off the ground but front ones on the ground.

When we spin one of the rear wheels the opposite wheel spins in the opposite direction. I've tried to turn the drive shaft while in neutral (motor off...we were changing the tranny oil and filter) and it showed as if wanted to turn both wheels in the same direction (4 high unlock) but with the front wheels on the ground it's logical that nothing will turn, i assume. In the same state, when I shifted through the 4x4 selections we saw no movement in the diff (with the cover off) but heard the transfer case working.

If I unplug the connector on the diff does the elocker unlock or does it "fail" in a locked state? Can I tell if unplugging connector on the diff has made a difference with the vehicle up in the air in its current state or do I really need to have the vehicle running to see if it has any effect?

Thanking anyone that can care to give an insight before hand.

 

I've read that the problem could lie in the actuator for the locking clutch at the transfer case, or the problem could be in the TCCM (transfer case control module). The most common problem is said to be in the actuator.

I've been bleating on about getting a service manual but the owner has been holding off...can anyone help me in locating these parts?

 

After more in-depth investigation on the TCCM I've somewhat ruled it out as it seems to be sending the orders upon pressing the selection with no erratic behavior, but leaves me to ask if I should consider that it is not sending the info to unlock the diff? Doesn't seem very likely, does it....?

Moving onto the actuator (I think I've found it Googling), what role does it have to play? Does it send information to the rear axel to lock or unlock. I still don't understand how the transfer case has anything to do with an unlocking diff. I can only add that when I selected 4 low (locked) it I got the same sort of mannerisms on the front as well as the back when moving on pavement, full steering lock.

As mentioned, I'm having problems mentally connecting the transfer case to diff lock, any insight on the missing puzzle piece would be appreciated.