4wd disengagement issue

Hello!

I experienced a strange issue yesterday with 4WD system in my Jimny, which has electric (bush button) transfer box.

Short story:
The car in reality did not return from 4WD-H to 2WD, although it signaled to me that it did. So I drove in 4WD-H on tarmac thinking that I was driving in 2WD.

Long story:
I drove in 4WD-L on a stretch of a rough gravel road, and I stopped just before reaching tarmac. I then pressed the clutch, changed drive mode do 4WD, and then to 2WD.
All operations appeared to have completed normally. The yellow 4L, and then the green 4WD lights turned off.

I proceeded to drive on the tarmac, supposedly in 2WD mode. After a few kilometers, I suddenly noticed that my steering has become excessively heavy.

At first I thought that my servo pump (power steering pump) died, so I stopped to investigate. I performed a visual check under the car, no oil leaks. I then tried steering left and right in place, no issues. I then continued driving forward, but the steering was again excessively heavy during vehicle's motion.
It was hard to turn the steering wheel, and when I turned it and released it, it would not straighten up on its own - it wanted to continue the trajectory where I lifted my hands from it.

Unfortunately it did not occur to me that maybe I got transmission wind up! I mean, I was supposed to be in 2WD!
So I continued to drive for another few hundred meters because I had no place to stop by the road. When I finally saw an easily accessible meadow next to the road, I steered onto it. It was a wet grass and the steering immediately became normally light as soon as I reached the meadow.

It occurred to me right then! I got transmission wind up in bloody "2WD"!

I then stopped on the meadow, engaged 4WD, and then disengaged it. After that, everything worked normally, even on tarmac.


Big questions:

It appears that the car did not disengage the front axle the first time when I changed drive mode from 4WD-H to 2WD by the pushbuttons on the electric transfer box controls. Therefore, I was still probably driving in 4WD on tarmac all the time (although no 4WD light was on on the dashboard).

Has this happened to anyone else? What could cause the drive selection system to misbehave so? How could I inspect or test for the possible causes? How serious is this issue?

I had problems with mine and it was one of the hubs sticking because of too much grease blocking one of the vacuum ports.

Well my hubs or anything on the front axle have not been serviced since I bought the car a year ago. I only changed differential oils a year ago.
So could it be that hubs got stuck due to that grease, although nobody tampered with that for a long time?

My opinion is that this is a dangerous issue, when a car does not disengage the front axle, although it informs the driver that it did, by turning off the dashboard lights.
I mean, it took me a while to realize what is going on, but my wife probably would not, and would either keep on driving until terminal transmission wind up failure occurred, or just stop and call for help.

What can it be done as a preventive maintenance measure against the occurrence of this issue?

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Now I have an additional problem. I am afraid that the transmission wind up which I had, was wound up a little bit too much. But the below issue might not be related. I don't know.

First, I drove over long dry grass meadows during the last night, with a lot of turning left and right. Although dry grass should not be slippery, I had to drive in 4WD-L 1st and 2nd gear in order to control my speed by throttle because of possible sudden ground undulations. However, my steering wheel did not become heavy at any time, so I don't think that I wound up the transmission at any time.

After that, I drove in 4WD-L on a bad, twisting, mostly dry gravel road, and then I noticed a problem.
When I am either in 4WD-H or 4WD-L, and when I am turning a bit sharply to the right on a hairpin bend, I hear repeating clunks from somewhere in or around the front axle, probably on the left side. The frequency of the clunks increases as I decrease the turning radius (as I turn more sharply). The clunks to not occur when turning radius is relatively large (I only heard them on hairpin bends).

When I am turning left on a hairpin bend, I hear the same clunks, only less.

When I am turning in 2WD, everything is OK.

4WD system engages and disengages normally, and front wheels do get torque when 4WD-H or 4WD-L is engaged (tested in a muddy spot near the end of the journey - in 2WD I was stuck, but in 4WD I got out just fine).

What could be the problem?

In the first instance it is prudent to reverse a few yards in a straight line when coming out of the 4x4 just to remove any potential tension in the transmission regardless of what hubs are fitted, though manual ones do seem to better at disengagement in my experience than vacuum ones.

Secondly I think you have busted a cv joint. In the first place avoid using 4x4 and as soon as possible get the steering knuckle open and examine the cv.

i tought about that as well, but wouldn't it also manifest itself in 2wd?
i remember a guy at the portuguese forum that had a busted cv and it would knock everytime he turned, and eventually one of the wheels would not turn.
could it be a damaged half shaft?

Not necessarily, it would depend on the nature of the damage to the cv and it's position at rest in relation to the the steering plane. For example if the damage was fairly minor and came to rest facing downward then the side to side motion of the steering could potentially not affect the cv. Equally though if left alone for too long the potential for catastrophe increases dramatically.