Autohub unlocking?

[Northcountrywood]

Noticed when I'm in 4hi with hubs in the "auto" position, they unlock when I come to an extended stoplight. When I start out, just the rears spin and then engage after I left off the pedal.

Is this normal? They are vacuum actuated right? Could I have a leak or just not pulling enough vac at idle?

Considering it's been snowing just about everyday since November, I switched to the locked position, but the autolock is helpful when going from clean to unclean roads so I'd like to figure this out.

Thanks in advance.

[Bart_3500]

Yes they are vacuum operated. Have you notice that your heater/ac moves to the defroster position? If so then you have a vac leak. I do and have been searching for a thread that talks about it. Haven't found it yet, but when I do I'll let you know.