Originally Posted by peteharvey

I used to have this problem when my 3GS was 4 years old.
I took it to the dealer and they said it was because my battery needed replacement.
After they replaced the battery, the self-dipping rear wing mirrors worked perfectly again.

Four years or so later, my 3GS's battery got old again, and the same auto-dipping wing mirror problems resurfaced.
I replaced the battery, and all was perfect again.

In other words, as the battery gets old, the battery voltage drops, and the auto-dipping rear wing mirrors on reverse play up...