Tis the week for lock gremlins...

My '84 SD had me locked out of the trunk this week. It seemed to be related to the warmer weather. I tried it early when it was cooler out, it unlocked.

A closer look revealed the '84 300SD has an electric servo motor in addition to the vacuum actuator for the trunk lock. The servo is driven by the factory alarm system to lock the trunk and had become stuck in the locked position. Simple fix... unplugged it. Trunk still locks/unlocks with the vacuum system.

Such a simple, reliable automobile. 30 years old and everything works perfect... except for the alarm.