# [Tutorial] How to fix a bad GPS on Galaxy S3 (verizon)



## toxicoder

Mod Type:: Mod

Difficulty:: Easy

Mod Status:: Stable

Apply In:: Other (See Description)

Requires Root:: No

Source:: 
In my case, the GPS would take about 10 minutes to lock on each time I launched an app. Even then it was very inaccurate, off by about 300-500 feet. I believe that the cause is related to the /efs partition on the phone but am quite uncertain. I made this tutorial because I spent about 15 hours of searching the internet and trying different "fixes" all of which failed to help.

I do know that this is a *guaranteed fix for the GPS.*

*Note: This process should work on any phone, but the details such as download links will be referring to the Verizon Galaxy S3*

*1)* *Begin by creating a nandroid of you're current set up.* Later you will flash back to it, so at the end of this process you will be exactly where you started but with a working GPS. The reason this will work even though you're nandroiding back is because the nandroid only copies certain partitions. The partitions creating the bad GPS problems is not part of that. So this process will restore those other partitions, that we really don't care about, back to factory

*2) Backup internal storage/SD because it will get wiped*

*3) Use odin to flash back to stock original. [background=rgb(248, 248, 248)]I535VRALF2[/background]*

*4) Once loaded, skip any type of customization like linking google account because you're immediately wiping.*

*5) Open phone and dial *2767*3855#.*This will factory reset the whole phone, all partitions not just /data /system like CWM wipe.

*6) Root phone, I recommend this one click method *http://forum.xda-developers.com/showthread.php?t=1706588

*7) Use EZ-Unlock to unlock the bootloader *https://play.google.com/store/apps/details?id=com.mmmeff.ez.unlock&hl=en

*8) Use EZ-recovery to flash clockworkmod recovery*

*9) Boot into recovery and restore from your nandroid. *

*10) Don't forget you have the radio from the **[background=rgb(248, 248, 248)]I535VRALF2 [/background]**so update your radio if you want.*

*11) Optionally use this GPS mod to improve GPS even more *http://forum.xda-developers.com/showthread.php?t=1880411


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## Goose306

> In my case, the GPS would take about 10 minutes to lock on each time I launched an app. Even then it was very inaccurate, off by about 300-500 feet. I believe that the cause is related to the /efs partition on the phone but am quite uncertain. I made this tutorial because I spent about 15 hours of searching the internet and trying different "fixes" all of which failed to help.
> 
> I do know that this is a *guaranteed fix for the GPS.*
> 
> *Note: This process should work on any phone, but the details such as download links will be referring to the Verizon Galaxy S3*
> 
> *1)* *Begin by creating a nandroid of you're current set up.* Later you will flash back to it, so at the end of this process you will be exactly where you started but with a working GPS. The reason this will work even though you're nandroiding back is because the nandroid only copies certain partitions. The partitions creating the bad GPS problems is not part of that. So this process will restore those other partitions, that we really don't care about, back to factory
> 
> *2) Backup internal storage/SD because it will get wiped*
> 
> *3) Use odin to flash back to stock original. [background=rgb(248, 248, 248)]I535VRALF2[/background]*
> 
> *4) Once loaded, skip any type of customization like linking google account because you're immediately wiping.*
> 
> *5) Open phone and dial *2767*3855#.*This will factory reset the whole phone, all partitions not just /data /system like CWM wipe.
> 
> *6) Root phone, I recommend this one click method *http://forum.xda-developers.com/showthread.php?t=1706588
> 
> *7) Use EZ-Unlock to unlock the bootloader *https://play.google.com/store/apps/details?id=com.mmmeff.ez.unlock&hl=en
> 
> *8) Use EZ-recovery to flash clockworkmod recovery*
> 
> *9) Boot into recovery and restore from your nandroid. *
> 
> *10) Don't forget you have the radio from the **[background=rgb(248, 248, 248)]I535VRALF2 [/background]**so update your radio if you want.*
> 
> *11) Optionally use this GPS mod to improve GPS even more *http://forum.xda-developers.com/showthread.php?t=1880411


So, you're telling users to ODIN back to stock then SIM reprovision?

Couple things:

First, internal SD isn't formatted on a reprovision code. Its just a factory reset. You will only wipe internal SD if you do a factory reset from stock recovery, that's what is causing that.

Second, SIM reprovision has absolutely zilch to do with the GPS. Completely separate radio/reception/firmware... etc.

The mod will likely do more as its improving the number of NTP pools in the gps.conf file along with supplicant information. The Play Store app GPS Status also helps as it refreshed the AGPS data (assisted GPS - that is, satellite/pool information, using WIFI and tower triangulation)

If you were seeing 300-500ft inaccuracy there is something else majorly wrong. Either its not pinging the sats right, or worse. Sounds to me like its not pinging sats at all (no lock on) and its just getting the 300-500ft based on AGPS data (WIFI pings, tower triangulation most likely)

The simple fact of the matter is that restoring to stock will always help in resolving whether an issue is firmware or hardware related. But its not a catch-all to fix any issue. If your ROM has buggered up GPS code, flashing to stock, then immediately restoring your nandroid of the ROM with buggered up GPS code will put you back to square one.

My .02c.


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## jbzcar

Goose306 said:


> So, you're telling users to ODIN back to stock then SIM reprovision?
> 
> Couple things:
> 
> First, internal SD isn't formatted on a reprovision code. Its just a factory reset. You will only wipe internal SD if you do a factory reset from stock recovery, that's what is causing that.
> 
> Second, SIM reprovision has absolutely zilch to do with the GPS. Completely separate radio/reception/firmware... etc.
> 
> The mod will likely do more as its improving the number of NTP pools in the gps.conf file along with supplicant information. The Play Store app GPS Status also helps as it refreshed the AGPS data (assisted GPS - that is, satellite/pool information, using WIFI and tower triangulation)
> 
> If you were seeing 300-500ft inaccuracy there is something else majorly wrong. Either its not pinging the sats right, or worse. Sounds to me like its not pinging sats at all (no lock on) and its just getting the 300-500ft based on AGPS data (WIFI pings, tower triangulation most likely)
> 
> The simple fact of the matter is that restoring to stock will always help in resolving whether an issue is firmware or hardware related. But its not a catch-all to fix any issue. If your ROM has buggered up GPS code, flashing to stock, then immediately restoring your nandroid of the ROM with buggered up GPS code will put you back to square one.
> 
> My .02c.


Having had to reprovision at one point, I can say that it *does* wipe your internal storage.


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## landshark

Development section is for threads for ROM, kernel, and mod releases by developers only. Tutorial and general info threads belong in the general forum where this is being moved.


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## blaineevans

I hate when I have *a* bad GPS.

Sent from my SCH-I535 using Tapatalk 2


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## Goose306

jbzcar said:


> Having had to reprovision at one point, I can say that it *does* wipe your internal storage.


Really? What was it you had reprovisioned on. I haven't reprovisioned in absolute ages but I most definitely had done it quite a bit back when AOSP was first starting and had the major RIL issues. I could have sworn it never once wiped my internal SD. Maybe I'm mistaken and drank away the memories in the last few months, or did something change? I remember wiping my internal SD twice when using stock recovery after an ODIN flash back when I first got the device (and losing a bunch of pics, etc) but never remember reprovisioning and wiping the internal. Meh, maybe I'm wrong.


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## toxicoder

Goose306 said:


> So, you're telling users to ODIN back to stock then SIM reprovision?
> 
> Couple things:
> 
> First, internal SD isn't formatted on a reprovision code. Its just a factory reset. You will only wipe internal SD if you do a factory reset from stock recovery, that's what is causing that.
> 
> Second, SIM reprovision has absolutely zilch to do with the GPS. Completely separate radio/reception/firmware... etc.
> 
> The mod will likely do more as its improving the number of NTP pools in the gps.conf file along with supplicant information. The Play Store app GPS Status also helps as it refreshed the AGPS data (assisted GPS - that is, satellite/pool information, using WIFI and tower triangulation)
> 
> If you were seeing 300-500ft inaccuracy there is something else majorly wrong. Either its not pinging the sats right, or worse. Sounds to me like its not pinging sats at all (no lock on) and its just getting the 300-500ft based on AGPS data (WIFI pings, tower triangulation most likely)
> 
> The simple fact of the matter is that restoring to stock will always help in resolving whether an issue is firmware or hardware related. But its not a catch-all to fix any issue. If your ROM has buggered up GPS code, flashing to stock, then immediately restoring your nandroid of the ROM with buggered up GPS code will put you back to square one.
> 
> My .02c.


Your theory about the modification of the gps.conf is most certainly false. Restoring a nand overwrites the gps.conf so these step would immediately undo that when you restore the nand, but this method worked fine (even before applying step 11, that just improved the already working well GPS). GPS data is indeed contain in another partition of the device as well as the /system. If you take a look at the /efs you will learn this. Realize though that that is not the true physical location as the references there are more like shortcuts, and no not to the /system, they're to a partition not modified by any normal flashing, not even odin. You can look in zips, or tars, and see what partitions they hold data for. Only the Samsung factory reset code resets all the partitions on the phone. There are 12 partitions btw.

You also will have your internal sd cleared upon applying the Samsung code for factory reset. I had the backup step early on when you're still running your wanted config as it would be easiest at that point.

This is indeed a catch all fix as this process resets all partitions on the phone. Then after your restore of the /system and /data, the only interference are files like the gps.conf which are fixed in the final step of this tutorial by the agps fix linked in step 11.


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## JeffreyJDavis

For what it's worth (and I am a relative Newb):


This system works, and I have been battling GPS issues on my d2vzw for a long time (cyanogenmod induced?). currently running MOAR.
I seemed to have greatly imrpoved GPS performance after step 3.
The Verizon SIM reprovisioning code no longer works on Verizon for stock ROM images newer than ICS. Please keep that in mind as you download your STock ROM.(Choose an ICS, not JB, ROM).
I would also recommend backing up your EFS partition after step 7 using EFS Pro or something similar.

your mileage may vary.


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## mugger48

BTW on the s3 the screws holding the body together can come loose over time. Take the battery cover off and tighten them. That solved all my GPS troubles.


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