Can't write to Nuvi 660 SD

The card I have has a lock switch on it. Does yours have something similar to that?
This is just a guess as I never tried to read/write to the card in the lock position.

And I can read the card but can't write to it.
(write protect message comes up)

I have the same problem. I called Garmin Tech Support and the bottom line was they sent me a replacement 660. SAME PROBLEM!!

I still cannot read/write to/from the SD card. I tried different sizes and ONLY a 256meg SD card would work, nothing bigger.

Anyone out there have a solution?

I experienced the problem today on an SD card and the write protect switch was not completely in position. I moved it one way and tested, but same problem....moved it the other way and it worked fine.

these comments are all interesting. I may try to find a small card and see if it works and then call Garmin support.

Has anyone tried an actual MultiMedia Card (MMC)?

I was doing some research on mnwool's original question, but was confused by this statement, "I just picked up an SD card I had laying around and it is a single voltage MMC card."

Anyway, I don't have any mmc's only sd's. My other devices, like digital cameras etc state mmc or sd cards can be used. MMC is not mentioned in the Garmin manuals.
MMC's are 1.4mm thick and SD's 2.1mm
MMC's have 7 contacts, SD's have 9.
I wonder if the mmc has enough wiggle room not to make the appropriate contact with the 7 contacts on the card vs 9 on the device. If indeed the device has 9 like the sd card does.

This is probably not an issue since other posts state the same problem with sd card. SD's have write protect (hence the Secure Digital name), MMC's do not.

Maybe the write protect switch is afu, or in Mkahn's experience not fully in the unlocked position. I'm sure another card was tried with the same results.

Will these suspect cards read/write with a card reader/writer? Or just won't work right in the gps unit.

Anyway, just some thoughts.