General questions about OBD2 interfaces:
Are these more or less recent USB to OBD2 devices pretty much the same? There are many out there, but is it correct that if the device connects to the port and can read and write, then it is all a matter of software after that point? Are the devices tied to proprietary software, or is the OBD2 port generic enough that any software will work with any (recent) interface?
If OBD was really a standard, there would be 4 pins on the connector. Instead there are 16 pins. There’s the old GM standard pins, the Ford pins, the European pins, the current Toyota pins, the Leaf pins…..
The connector that plugs into the OBD port has a microcomputer in it that translates some subset of the OBD possibilities into a serial protocol. That serial protocol can be delivered to a PC via USB or Bluetooth.
There are currently two major device standards in use, ELM and J2534. The cheap devices all use ELM, and most are imitations of the devices made by ELM Electronics.
ELM is ok for slow speed queries of the CAN bus on current Toyotas. There are a few premium ELM protocol devices that are fast enough to handle the full data rate on a Prius. The ELM protocol does not support the K-Line interface on the Prius, which means that TPMS, Gen2 keyfob, and Gen2 option setup cannot be supported by any software on the PC.
J2534 is required for use with Techstream. Which means the Denso interface that dealers use, the Mongoose, the Tactrix, or one of the Mongoose imitations like the Mangoose (I kid you not…). The Tactrix has really only been debugged with Subaru/Mitsubishi vehicles. I don’t have any experience with the Mongoose clones.
Note: the MVCI only are compatible with Windows XP, so you’ll want to confirm first. I purchased a Netbook to use with them, as it is smaller than my laptop and easier to maneuver in a car.