We are having a problem with the automatic locking system on our 1997 E-320. It is intermittent, no matter where you direct the key aim. We have checked out both keys--the batteries are fresh--and it still happens. Our mechanic experienced the same thing but could not find anything malfunctioning. Has anyone had this problem? Is there a solution?

You might want to double the electrical contacts in your key(s), the contact tabs tend do get weak over time causing intermittent/sporadic battery connection.

We will check that out. What is confusing is that when you hold in the button on either key, it emits a strong red light.