The 4wd system on our little Jimny uses clever vacuum operated free wheeling hubs. The hubs themselves seem sturdy and reliable enough, but one wonders how those little vaccuum lines under the can last in mud and road salt. So when our 4wd system stopped engaging while the 4wd light would only flashed in alarm, the most logical cause seemed a vaccum leak. Of course the vacuum lines are not designed as regular service items, so they are tucked away in some of the darkest places under the car and finding the actual leak proved to be a bit of a challenge.
Here, with brake disk removed, you can see one of the two vacuum lines connecting to the hub, just above the ABS wheel. The front one is the "Disconnect".The "Connect" line is tucked away between the back plate and swivel housing. It is actually possible to suck on one of them to activate the corresponding function.If you can get at them that is...
After some easy dismantling the cause of the leak showed itself
This metal vacuum line was rusted through near the junction, just above the front axle.
An easy fix in a difficult place.Two short lengths of rubber hose, a union and a short copper pipe were all that was needed to fix 4WD and that 4WD light is steady now.