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  1. #1
    Junior Member
    Join Date
    Apr 2019
    San Diego CA
    Rep Power

    Default Incorrect Time - GPS Rollover - (MTK) Mediatek Chipset

    After visiting this website, I got interested with GPS repair and bought broken units. I couldn't fix what looked like a time zone problem, ..... GE updates, Gps firmware replacement, Reset, etc. The only solution I found was to replace mt.nvm in the .System/GPS folder with one from a good unit having the same GPS firmware version.

    After GPS sync, if the YEAR is wrong in the WORLD CLOCK app, you probably have this rollover issue. Without the app, look for year in SHUTDOWN CAUSES, ( Developer Mode -- map,speed, hold speedmeter ).

    Units I found with this issue:
    Gps firmware 2.00b Nuvi 255 HWID=B1091
    Gps firmware 2.60 Nuvi's 1100 HWID=B1106, 1300 HWID=B1104, 3760 HWID=B1101
    Gps firmware 3.00 Nuvi's 40 HWID=B1350, 50 HWID=1350

    I tried to figure out the how's & why's, but I'm at a loss.
    1. Backed up region 41 on a good nuvi 40.
    2. Deleted mt.nvm from GPS folder and found good file regenerates after gps lock.
    3. Replaced mt.nvm with bad file from wrong firmware ver 200b instead of 3.00.
    4. After reboot, time stay ok, until user data is erased, and now timezone issue is permanent.
    5. Garmin Express does not detect any issues.
    6. Loading Original good backup 41 temporarily resolves issue until next user data clearing.
    7. Replacing mt.nvm file is the only fix, surviving user data resets.

    I can only surmise these broken units were caused by incorrect file replacements.
    Last edited by zuvicon; 7th August 2021 at 12:35 AM.

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