4 wheel drive issue ?

[Abom]

Ok, strange issue with my 4 wheel drive system.

For reference, I have a 96 Ex, which I realize has the center axel disconnect.

I was driving up a slightly muddy / steep dirt road, so I stopped, put the Ex in neutral, threw the switch to 4x4 Low, put the transmission into "1" and drove up the hill. No issues driving up it. When I got to the top, I stepped on the gas a bit more, brought the RPMs up quite a bit, and the 4x4 lights (both the auto and low ones) blinked 3 times and both went out. Interesting. I had the same issue once before a few weeks ago, when driving on a different gravel road. Put the transmission into neutral, engaged 4x4 Low, drove off, this time in D (Drive), and same thing, when I got to a certain speed / RPM, the Low and Auto lights blinked 3 times and turned off. Both times when I've flipped the switch to 4x4 Low, I heard the front locking and feel the clunks. I'd since tried the 4x4 Low on gravel parking lots, putting it in neutral, then 4x4 Low, then into "1", and while I haven't gotten the RPMs or speed that high, I can tell all 4 wheels are indeed spinning, and the system does work. It only seems to be at higher RPMs and speeds where I'm having an issue, which makes me think there's a safety device that disconnects the 4x4 Low when you go too fast ?

Also, I have noticed that if I try to engage 4x4 Auto while "on the fly", as far as I can tell from gravel roads (the real test will be on snow I suppose), the front axel won't connect, as in, it seems like the front wheels aren't being engaged when the rears spin. However, if I put the transmission in neutral, at a dead stop, and put the Ex into 4x4 Auto, and do the same "step on the gas on loose gravel" test, the font wheels seem to be engaged perfectly fine. Important to note is that the 4x4 Auto light turns on no problem, and never turns off or blinks, even if it seems the front wheels aren't kicking in. So from dead stop in neutral, turning on 4x4 Auto seems to work, but turning it on while cruising doesn't.

I don't know if it makes any difference, but the previous owner lived in an area where there was no snow or anything. When I purchased the Ex off him, he mentioned that he "tries to put it in 4 wheel drive at least once every year or so, so it at least gets used". My differential fluid has been changed, and ATF has been changed. O/D light has never blinked at me so far. Is it possible that he simply just hasn't used the system enough and it needs to be used more by me ? (boy I'd love it if that was the problem )

The Ex has about 110k miles on it, runs very well and doesn't seem to have any other issues other than minor unrelated stuff. The only other thing that's anywhere close to being related is a slight delay shifting between gears 2 and 3, most of the time when going up a hill, although I've already read about the issues regarding the 1-2 and 2-3 shifting, and my issue seems to be a rather mild version of it.

Any insight would be greatly appreciated

 

[budwich]

Likely cause is your hall sensors on your transfer case.... either cleaning or bad. Another test is to put your 4wd in "auto" and go over ~35 mph or so.... same thing will happen, it will drop out of 4wd and flash. The reason is that the computer is unable to compute or understand speed differences in your two axels.

 

[Abom]

Hmmmmm, this makes complete sense I suppose. When testing the "Auto" part and going over 35mph, should it drop out and flash whether it's actually using the 4 wheel drive or not ? I'm nearly positive that the light stays on regardless of how fast I'm driving, without the front wheels needing to be engaged.

 

[budwich]

If its a sensor issue (as mine is), in 4w auto, when I exceed the "magic speed", it drops out and lights go off and then flashing occurs shortly there after. If not, then you might have a different flavor of problem. I have never "rev'ed" up my 4w low other than going very slow up ramps or a couple of steep gravel hills.

 

[Abom]

Ok, so upon testing, I can go 60 mph in auto and the light stays lit no problem.

Anyone else have any ideas ?

 

[Abom]

Ok, so I retested the 4 wheel drivetrain yesterday night, in the exact same place as last time.

Auto 4x4 now engages no problem "on the fly", strange. Also, my 4 low seemed to stay "locked" and didn't turn off as mentioned before.

I am beginning to think the system simply needs to be used, as it has never in it's 10 years of existance ever actually been used before (Last owner lived in an area with no snow, sunny most of the year, and never took it into the bush).