WARNING: Anyone who purchase Myron & Davis aftermarket NAV

I just had a nerve-racking experience with my aftermarket Myron and Davis NV7TPR1 NAV unit I purchased and installed last year. I got a fatal message on the “Accept” screen that said there was a corrupt file on the SD card:

LUA error – script load
Script name:\SD\memory\gogo\bin\script\800x480\MAP.LUAC
Error message:\SD\memory\gogo\bin\script\800x480\MAP.LUAC: bad constant in precompiled chunk

I called M&D tech support and they knew this error well and even stopped me before I could read it off. They told me I needed to contact the eBay seller and ask him to “warranty” me a new SD card! So far, I have not heard back from the seller.

Here’s another problem…you can’t just buy a new SD card and copy the contents from the original card onto it – it gives a different error message saying “Licensing error”. I guess the license “key” is locked onto the original SD card and cannot be copied. I still want a new SD card, but have a temporary work-around. I have a friend nearby with the same NAV unit and was able to copy his non-corrupted file called MAP.LUAC over my corrupted file. This seems to work for now, but I have little faith in my original SD card.

My suggestion to anyone who purchased this NAV unit is to copy all the files and directories from the SD onto your PC say under My Documents and put it in a new folder called Myron & Davis SD. You MUST turn off your anti-virus checker as it will immediately flag the autorun.inf file as a threat, which is a “false positive”. Your anti-virus software might even prevent you from copying this file. Once you have done this, you can then copy any of the files from your PC back onto your original SD should one of them become corrupted. But once you have a corrupted SD, this solution is too late so I suggest doing it before it happens to you (thanks to Bubbatech for the original idea).

If I get any satisfaction from the eBay seller, I will post back here with an update.

 

Thanks bubbatech for chiming in here. I contacted the original eBay seller and he said he doesn't deal with the SD cards and doesn't know about the issue. He no longer sells these units (no surprise there!). Anyway, since M&D claims it's the SD card which is provided by Gogo Navigation, odds are I will have to reach out to them for a replacement card.
Bubbatech: I will try your other suggestions on cloning the original SD card to see if the hidden license files can be duplicated. Thanks again for your reply and suggestions.

 

UPDATE: I have found a better solution than just backing up the contents of the SD card in the Myron and Davis unit. I have now successfully used Win32 disk imager which creates an exact "image" of all the contents on the SD card as a backup file on my PC. If you should ever have a NAV error where the system corrupts the SD card, you can easily restore the image file to the SD card and it will work perfectly again.

The problem is you must create this image copy of your Myron & Davis SD card BEFORE it gets corrupted. Here is a website so you can download, install and use Win32 disk imager: Win32 Disk Imager | Free Development software downloads at SourceForge.net

The first step is to create a folder on your PC (Windows) to store the image copy. When you invoke Win32 disk imager, you browse your way to this folder and then create a name for the image copy (i.e. M&D SD backup.img). Be sure your M&D SD card is in your SD card reader slot (usually drive F). It should show up on the far right side of the Win32 disk imager. Now select the READ button and allow the imager to create the backup image which takes several minutes depending on your processer. There's a green progress bar too.

Once you have the backup image, should your M&D unit corrupt the SD card, simply invoke Win32 disk imager, place the corrupted SD card in your PC's SD slot, select by browsing the image copy backup that you made and then select the WRITE button. It will restore your SD card to the good image and your navigation will work again.

 

Hello Xat0s, Sadly, my Prius was totaled in 2016 by a teenage boy who rear-ended me. I had to let the M&D NAV unit go with the car but got a few hundred added onto the salvage value of it. Maybe somebody else can help you.

Just an FYI...the original SD card that comes with the NAV unit is specifically coded to your system, so you cannot use any other SD card with it. SD stands for "secure data" and the M&D people made sure no other SD card would work in it. Best of luck to you.