Diff lock inop?

[Jolfa]

As per title, my diff lock doesn't lock the diff. The actuator can move freely, the switch lights up to say it's locked, but it doesn't lock.

I'm quite sure all vac lines are connected correctly but can someone confirm which one I should be looking for on the engine?

Only other culprit is the unit under the rear seats, how can I test this?

Any other likely causes?

[UrS4boy]

Diff lock 101

Have a read on the link below. Should help.

http://forums.quattroworld.com/s4s6/msgs/170940.phtml

[Jolfa]

Perfect, cheers!