EM7590 running firmware 04.00.04.00 won't download ephemeris data, no GPS sync

IoT Modules MC/EM Series
1

I have a new EM7590 that won’t get a GPS fix.

AT!IMPREF:
preferred fw version: 00.00.00.00
preferred carrier name: AUTO-SIM
preferred config name: AUTO-SIM_000.000_000
preferred subpri index: 000
current fw version: 04.00.04.00
current carrier name: VERIZON
current config name: VERIZON_004.000_000
current subpri index: 000

It sees satellites with good SNR using AT!GPSFIX=1,255,1000:

at!gpssatinfo?
Satellites in view: 9 (2026 07 28 1 17:19:23)
SV: 10 ELEV: 0.000 AZI: 0.000 SNR:31.500
SV: 15 ELEV: 0.000 AZI: 0.000 SNR:39.300
SV: 18 ELEV: 0.000 AZI: 0.000 SNR:30.400
SV: 23 ELEV: 0.000 AZI: 0.000 SNR:37.500
SV: 24 ELEV: 0.000 AZI: 0.000 SNR:34.900
SV: 29 ELEV: 0.000 AZI: 0.000 SNR:40.700
SV: 32 ELEV: 0.000 AZI: 0.000 SNR:39.200
SV:133 ELEV: 0.000 AZI: 0.000 SNR:41.000
SV:135 ELEV: 0.000 AZI: 0.000 SNR:40.100

The SNR values are very good so I don’t think it is an antenna problem.

Google told me:
Your EM7590 is running firmware 04.00.04.00, which has a known bug in its GPS/GNSS subsystem where tracking sessions crash, fail to download ephemeris, and repeatedly time out with FAILCODE = 4.

But this is the latest version of the firmware, published only last month.

The module is in an embedded PC running Linux, Ubuntu 24.04, and I have disabled ModemManager to debug this (the modem does get a good connection to Verizon with the ModemManager running).

2

how about using other firmware?
https://source.sierrawireless.com/resources/airprime/minicard/75xx/em7590/em7590-approved-fw-packages/#sthash.QuzdpHaC.K1Su9oj3.dpbs

3

I tried using the GENERIC, but it is the same version SWIX12C_04.00.04.00 as the Verizon, and it wouldn’t connect to the cell network (got provider mismatch).

The original version was 02 but it also wouldn’t get a GPS fix, so I downloaded the 04.00 Linux binaries and updated the firmware.

at!image?
TYPE SLOT STATUS LRU FAILURES UNIQUE_ID BUILD_ID
FW 1 GOOD 1 0 0 ?? 02.02.03.00?
FW 2 GOOD 2 0 0 ?? 03.01.02.00?
FW 3 GOOD 3 0 0 ?? 04.00.04.00?
Max FW images: 3
Active FW image is at slot 3

TYPE SLOT STATUS LRU FAILURES UNIQUE_ID BUILD_ID
PRI FF GOOD 0 0 0 002.000_002 02.02.03.00_GENERIC
PRI FF GOOD 0 0 0 002.001_002 02.02.03.00_ATT
PRI FF GOOD 0 0 0 002.000_002 02.02.03.00_TMO
PRI FF GOOD 0 0 0 004.000_000 04.00.04.00_VERIZON
Max PRI images: 25

OK

ati
Manufacturer: Sierra Wireless
Model: EM7590
Revision: SWIX12C_04.00.04.00 2026/05/05 15:32:04
SVN: 10
IMEI: 357999720307729
FSN: DX4516038101H1
TS.25: 2026.1.12
+GCAP: +CGSM

OK

4

How about the version 03?
You can try other PRI version as gps fix is not related to any network

5

It seems that the problem is caused by the M.2 to mini-PCIe adapter holding the modem. It has a SIM holder and a USB 3.0 interface for the SIM that we believe was causing RF and/or power noise that interfered with the GPS signals. Still working on a solution.