[FIX][JB]GPS Workaround for Jellybean

Revamped the entire OP to make it relevant for current roms.

Many users of the Epic 4g Touch have reported various GPS inconsistencies. While this seems to happen more frequently on AOSP-based ROMs (CyanogenMOD, PAC-man, Evervolv, AOKP, etc), it has been reported on TouchWiz-based ROMs as well. Below are a few tips and tricks to help fix your GPS.

FIRST: You will need the necessary tools to troubleshoot the problem.
Google Maps - The app we will use to determine if GPS works properly or not.
GPS Status (Optional) - Provides additional information about GPS performance. This shows how many satellites are in view, coordinates, heading, and other useful information as well. This can help to confirm wether you have a GPS problem or are just in an area without GPS reception.

SECOND: You will need the tools to fix the problem.
- Root-capable file browser (ES File Explorer is my personal preference)
- Mobile ODIN (Free version is available on XDA, but Pro is well worth it, as well as supporting Chainfire, one of the most respected devs in the Android community)

THIRD: You will need some files saved to your sd card. These will be flashed in recovery or Mobile ODIN.
- The EL26+CWM recovery kernel.
- Any Jellybean ROM you want to run.
***For TouchWiz ONLY* Agat's 0.3.0 GB27 Kernel with tREC custom recovery.
- A working GPS.conf (explained later)
- Goddly's ComaDose tweaks (not required if you use a standalone GPS.conf, but highly recommended. See his thread for details.)

FOURTH: You will need these files on your sdcard to temporarily return to stock if needed.
- The EL29 CWM5 Directboot Kernel
- The EL29 Tempboot ROM

METHODS:
I will post each method of fixing GPS, in order of time investment. Test GPS with Google Maps (and optionally GPS Status) after EACH METHOD. Please provide feedback on which method worked for you so that I may improve this guide further.

Method 1 - GPS Toggle
Try this first. It only takes about 10 clicks to do the whole thing, and it saves you from having to flash anything if it works.
1. Close Maps and any other location aware apps. Make sure to clear them from Recents to ensure that they are fully closed.
2. Go the your Location tab under Settings. Toggle GPS satellites off and on, then toggle Location as well (System Settings>Location Access>Access to my Location). This should result in a popup asking if apps can have your permission to use GPS.

Method 2 - New GPS.conf
All thanks to Goddly for allowing me to use his gps.conf.

Sometimes, the GPS.conf file on your phone can become corrupted or otherwise unusable. This will prevent you from locking on to any satellites, even though you may have one (or several) in view.

1. Make sure you have a working GPS.conf on your phone. This can be a standalone GPS.conf like the one attached to this post (extract the zip first!), or it can be one contained in a tweak package such as Goddly's ComaDose v1.4
2. Copy & paste the working gps.conf into /System/App using your root file browser.
3. Set permissions to the gps.conf to 0777 (rwxrwxrwx)
4. Reboot.
5. After booting, toggle Location (triggering the popup).

Method 3 - Lock on Stock
This is a tried-and-true method that was most frequently used in the early days of CM10. It is usually not needed anymore, but I am keeping it in just in case.

1. In Mobile ODIN, flash the EL29 CWM5 Directboot kernel.
2. Reboot, you should automatically wind up in recovery. If you do not go to recovery, pull the battery, wait 10-15 seconds, replace the battery, and hold vol+ and power.
3. Flash the EL29 Tempboot ROM (This will be in the Multiboot folder on your SD card, assuming you followed the instructions in the link above.)
4. You should automatically boot into stock EL29 Gingerbread.
(Optional) 4 1/2. Update Profile and PRL (if desired, you can't do this on AOSP so you might as well do it now)
5. Open Google Maps and get a GPS lock (you will likely need to be outside to get a good lock). Sometimes it helps to navigate to a random place.
6. ***WHILE YOU STILL HAVE A GPS LOCK***, power down the phone, then hold vol+ and power until you boot to recovery.
7. In recovery, Wipe Cache, Wipe Dalvik Cache.
8. Flash your ROM of choice.
9. Reboot.

Please reply to this thread with any questions/issues/feedback.

moparfreak426 said:

I havent multibooted this device.... Do u just make a folder on internal sd or do i need to..... Nevermind i guess i should google first

Sent from an Apple killing JellyBean

Click to expand...

Click to collapse

Detailed instructions are in the tempboot link in the OP.

moparfreak426 said:

ok... i read up on it and stuff.... i cant mount phone to pc... idk why so i put multiboot on sd card and moved it to root of device..... its froze moving the system.ext4.img......... should i be worried? phone is so laggy... hit power button to turn on off screen... response = roughly 10 seconds later

---------- Post added at 11:57 PM ---------- Previous post was at 11:43 PM ----------

Phone completely froze and reset.... So no gps lock for me:/

Sent from an Apple killing JellyBean

Click to expand...

Click to collapse

if you didnt get a good copy your multiboot wont work. Try downloading the file directly to your phone, and unzip it to the root of your internal with zarchiver.

Edit: apparently zarchiver can't extract to the root, or the system.IMG won't copy to the multiboot folder correctly. Try copying it again with your computer. Make sure it's on the root of your internal, not in /sdcard/ or on your external.

Failing that, nandroid your cm10, flash a tw-based gingerbread ROM with cwm5 recovery, get a GPS lock, reboot to recovery, flash cm10, reboot recovery, then restore your nandroid while on cwm6

Edit 2: what ROM are you on when trying to mount USB storage? It won't work on tw ICS or jb, and it might be disabled on aosp (Settings>storage > menu > USB computer connection > USB mass storage)

Lt_data said:

I was wanting to try this, but had a couple questions before I tried it:

Is the wipe of /data really necessary, or does it just help things run better?
Will this work on CWM6?

Also, with the PACman builds after 1/12, you don't have to flash Paranoid Preferences seperately.

Click to expand...

Click to collapse

1: Technically no, but a /data wipe is always recommended. If you have issues after this procedure, wiping /data is your first step to fixing them.

2: You start out on the cwm6 included in our AOSP kernel. You flash the el29 cwm5 directboot kernel with mobile odin, then flash the el29 multiboot (which requires the el29 kernel). When you are done with your prl updates/gps fix/dialer codes, you then reboot recovery and flash your AOSP 4.1 again, which puts you back on the AOSP kernel that includes cwm6.

Updated OP.

Re: [FIX][JB]GPS Workaround for AOSP-Based 4.1.2

Lt_data said:

Does it matter that AOSP ROMS now use /sdcard instead of /emmc for the internal card? I tried the steps (without any clearing of cache or data, doh) and it just bootlooped. I was just wondering if that would be a factor?

Click to expand...

Click to collapse

Talking about the multi boot I assume? It goes in /sdcard/. This is the root of the phone's internal storage when mounted as USB mass storage via PC.

I don't even remember when AOSP last used /emmc/...July I think? Alpha CM9 I think. Before Chris41g started releasing like 5 test builds a day. At any rate, long before jellybean, which is what this guide is for.

And don't forget to wipe the things, or you will have problems.

Sent from my SPH-D710 using xda app-developers app

Lt_data said:

/sdcard IS the internal storage. The actual SD card mounts to /external_sd. I realized this after 45 minutes of trying to make a multiboot folder in / unsuccessfully.

Click to expand...

Click to collapse

*facepalm* You are correct. My mistake.

I was thinking root of internal storage when phone is mounted via USB. I could never get the multiboot to extract entirely on the phone, it would just freeze for a while, then force close ES, then eventually reboot.

The correct path (when flashing) is /sdcard/multiboot/EL29/Boot_EL29.zip. So make sure your install matches this, or you will have problems.

chaosacolyte said:

Hello, I have tried fixing my gps lock with this method three times. I even "one clicked" back to EL29 rooted for a fresh(er?) start. While in the EL29 temp boot, I can get either a 9/9 or 10/10 GPS lock( all three attempts), power down while in the lock (using google navigation), and follow the rest of the steps. Once I flash back to my CM10.1, or a clean install of 10.1, I start up GPS Status, and it tells me 0/2 sattelites locked. What is odd is that the two it tries to connect to changes every second or so to another random sattelite. So I see something like 21->03->18->12->30->14->22->32 etc. Any tips? Would flashing a new modem help? I originally had FL24 (i think) when I tried this method the first two times, and EL29 the third time (because Odin One Click reset it back to EL29).

EDIT: oh I realize this method works for 4.1.2, but would it also work for CM10.1, which is 4.2?

Click to expand...

Click to collapse

sorry for the delayed response. This method should work for CM10.1, but I have not tested it personally. Post your results and let everyone know if it works for you.

Re: [FIX][JB]GPS Workaround for AOSP-Based 4.1.2

Gazzuk said:

I did OP fix with el29 with no success. (Used to work for me)

However..

After trying a few ROMs. I noticed I could update prl/profile in jellyverse v.4 (FL26) and get a lock. At this point curiosity struck so I Mobil Odin cwm el26, wiped data/cache/dalvik **skipped format all zip** and I flashed a JB aosp ROM and ICS modem. Long behold I can get GPS locks on my favorite ROM now.

So if el29 doesn't work for you (It did at one point for me but not anymore) try this method. It worked for me. :thumbup:

GL

Sent from my SPH-D710 using Tapatalk 2

Click to expand...

Click to collapse

Never use a format all script with this fix. It will cause problems.

Better yet, never use a format all script ever, unless specifically directed by the OP.

Sent from my Epic 4g Touch on PAC-man v19.3

Re: [FIX][JB]GPS Workaround for AOSP-Based 4.1.2

chaosacolyte said:

sorrry for my late reply too, . The problem seems to be in the CM10.1 rom itself, because there are others in the thread (edit: the "wild for the night CM10.1 thread)... tl;dr: GPS locks even though apps dont report it locking in CM10.1

Click to expand...

Click to collapse

That would explain why I hadn't heard... I haven't been checking that one, I was on phantom's cm10 and hadn't been following WftN

Sent from my SPH-D710 using xda app-developers app