we're gettin a 2002 4x4 manual trans tracker we were told it has a bad actuator  I havent even looked at theproblem yet but do know my older trackers dont have anything  by that name  anybody know what it is and does? just tyring to get some info as to what Im lookin for or at when I get to it next week

2002 uses a vacuum ( maybe pressure!) pump to engage 4x4 in the diff. Usual problem is a bad air hose, could also be a pump problem or possibly a leaky seal in the diff.

The system as rhinoman stated is vacuum-acutated. It is similar to that found in Jeeps.

Instead of disconnecting the drivetrain from the wheels at the hubs, the vacuum-driven mechanism disconnects in the axle itself. In the case of the Sidekick/Tracker, the mechanism is inside the differential.  The Jeep (Dana) front axle has a vacuum-acutated slide joint on the long side of the axle.

This device is not to be confused with a locker!  It only disconnects one of the axles from the differential.

It's sorta like locking hubs not not quite, in my opinion...    If I had the time, I'd install an earlier dif in the front of my '02 4-door and then slap locking hubs on it...

I hope that this helps!

thanks that will help  I figured it was something like the yj dana -30 in my spare junk pile

99~05 Grand Vitaras & Trackers - do NOT use vacuum, but rather 5~8 psi positive pressure to engage the "axle lock clutch" in the front differential.

We stand corrected on that point.  Positive pressure instead of a vaccum.

Thanks fordem!