Which is the better diagnostic tool for Subaru: VXDIAG SSM3 or FreeSSM?
SSM III: the short form of Subaru Select Monitor, is an OBD based tool that allows configuration and customisation of the Engine Control Unit (ECU) and Transmission Control Unit (TCU), which is great for diagnostic and tuning purposes.
FreeSSM: FreeSSM is software for Subaru diagnosis using a cable with a authentic FTDI FT232RL chipset. Combined with a specific OBD Cable, you can customise and tweak your own vehicle at home using a Windows computer!
1) FreeSSM
FreeSSM accesses ECMs over a SUBARU-specific protocol (called SSM2), which is actually a modified version of the ISO-14230-protocol (KWP2000).
Operating system: Windows XP, Vista, Windows 7
Diagnosis : Yes, data trouble codes (OBD2), measuring blocks (Data / Switches) , adjustment values (Engine / Transmission) , system component test (Actuators / Others) (Engine Only)
Customization: Yes
ECU programming: No
Remote/Key programming: No
Reprogramming: No
Vehicle coverage: Subaru from year 1999 to 2009 incl. Impreza, Forester, Tribeca, Liberty, Baja, Outback
Compatible Hardware: FreeSSM cable, vag cable or elm327 (need luck)
2. SSM III
Operating system: Windows XP; Vista; Windows 7; Windows 8;Windows 10: Need luck
Diagnosis: Yes, full system diagnosis, Bi-Directional tests
Customization: Yes
ECU programming: Yes
Remote/Key programming: Yes
Reprogramming: Yes
Vehicle coverage: works with Subaru models from year to 1998-2018
Compatible Hardware: Hitachi HDS3000 or the newer Denso DST-i or VXDIAG VCX PLUS
In conclusion:
FreeSSM is a must-have tool for Subaru DIYer. It focus on fault code resetting and customization function.
SSM3 is a dealer level diagnostic system for professionals. It allows to program keys, TPMS etc, while FreeSSM does not. You can add other car brand software license to the vxdiag vcx unit as well.