that's very interesting, i'll have to go try that out before it gets taken apart, much easier!

Isn't there a way you could put a metal rod into the air fitting to push on the actuator mechanism and keep it engaged without having to open up the diff?  I had a 2nd gen Tracker in the past but no longer do.

I doubt it - the air fitting is on the bottom of the diff housing and connects to the actuator internally with a rubber hose.

i have on in my garage i'll take a look at it tomorrow. it is taken out of the housing but from what i can remember you would have to slide the ring over to get it engaged. there is a diaphragm that pushes the ring over. by sticking a rod in through the air fitting you would not get the ring to slide over the full diameter. full diameter of the ring has to be pushed over to be engaged. so if you could slide the rod in you would only have pressure on the bottom part no enough to engage the diff. but i will look at it tomorrow well im picking at stuff in the garage.

if i remeber my camera i will take a pic or video to show how it functions. i alway find it easier to understand stuff better when you can see it.

In the first pic you can see the air line hose where it hooks into the air actuator collar inside the diff.  In the second pic you can see the metal air line (removed in my hand) that threads into and passes thru the diff housing to connect to the air hose running into the air actuator collar.  When inflated that collar inflates evenly and pushes /engages the cogs within the diff.

The third pic shows the hose (in the middle of the pic) that connects the two air nipples inside the diff.

That's why running a line thru the air line probably wouldn't work well for engaging the cogs effectively and reliably.

Thanks for the pics.  That is quite a complex setup.  Both of my 2nd gens were relatively new so I never had any issues with the mechanism.  How common is it for it to go out as they get older?

Ahhh - how do I put this - I don't think failed actuators were a common problem - but - at the same time, I am aware that the free wheel clutch assembly was a known weak point, and there are actually two possibly three different versions as Suzuki made a number of improvements along the way - even the aluminum housing and third member have been redesigned.

I have an Africa market 98 (North America was the last to get the second gen), and the only problem I have experienced (with the 4WD) is a failed air pump

I agree with Fordem.  The actuator within the diff appear to be pretty durable.  The air pumps are prone to moisture penetration and corrosion on the internal wiring contacts.  Fordem (I believe) had a thread on disassembling and repairing them.  I have re-soldered a corroded contact in one and brought it back to life.  The small diaphragms in them can also rupture preventing them from compressing/pumping  air as well.  

Out of three air pumps I have worked on, one had a corroded connector which allowed a wire to literally separate causing the pump to fail and a second had a ruptured diaphragm. The corroded wire was repairable, the diaphragm wasn't.  On the third pump, the mounting bracket had been severely bent from impact of a collision.  The actual pump still worked perfectly.  All three had inidications of moisture penetration of the housing  with associated corrosion to various degrees inside the housings through the seals or where the wires entered the pump housings.  This with the fact the pumps are tucked away from the elements pretty well behind the bumper.  Of course if the operator run their truck thru open streams/puddles/creeks bumper deep... the pump is down in the water.

I suppose yet another thought/idea to improve the reliability factor of the air actuated front diff would be to replace the factory stock air pump with regulated air pressure provided from say... an ARB type, more durable/reliable aftermaket compressor that could be mounted under the hood,  up on the inside fender by the driver's hood hinge.  That placement wouldn't work if your truck has ABS, though.  Still, its another idea.  Plus the pump could also be used for onboard air for out on the road or trail. 

is it an air pump or vaccum pump, the stock unit?  could i hook one of the hoses into the engines vaccume lines?

Why, after reading a thread that talks about air pumps, and even suggests using air from a compressor, would you ask if it's an air pump or a vacuum pump?  If you don't believe what's already been written, why would you believe a fresh answer?

It's an air pump, and yes, you can hook one of the hoses into a vacuum line, but, don't expect it to engage with a vacuum, it needs positive pressure.

why ask?  to learn.  also because the pewney hoses are not clamped- they look like vaccum lines.  most positive pressure hoses are clamped, to prevent leaks.  i figured id ask because i sold my "air" pump to a needy customer.  there are 2 hoses so maybe if i put vaccum to the opposite line it might stay engaged?  im going to add locking sidekick hubs later- and its only a mud toy. 

The only place there are two hoses are at the pump itself - an intake that runs up alongside the radiator support, and the outlet to the differential - the system works with 6~10psi, no need for clamps - and the only way to make it stay engaged without the air pump is to remove it and tack weld it in the engaged position.

thanks for the info.  i will likely get another pump and possibly relocate it higher- away from the mud

or change  diff gears and get away from sotf