ELM327 + 98 Subaru = NoGo

I recently puchased an el cheapo, ELM327-based USB OBD-II interface on eBay:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=320349644502&sspagename=STRK%3AMEWNX%3AIT&viewitem=

Works great w/ other cars, but I can't seem to get it to communicate correctly with my 1998 Subaru Lagacy GT wagon.

I've tried all the common freeware, shareware, and demo software (ScanTool.net, OBD2Spy, wOBD, ScanMaster, DataPro), and it just doesn't want to communicate w/ that particular car - won't read codes or connect at all. I get various communication error messages, and a few of the programs will crash altogether when I try to connect to the Subaru.

Any advice will be much appreciated. Was Subaru using a non-standard protocol in 1998 or something? Or maybe I just need to buy a better USB interface with superior firmware compared to the $20 Chinese gizmo I'm currently using?

best,
JohnB

Hi John,

The Chinese/Taiwan/Hong Kong Elm327 knock-offs are hit and miss. The main problem is their quality control almost doesn’t exist. You might need two or three more of the same scan tool to connect on every vehicle out there.

You can try connecting to the scan tool using HyperTerminal or Tera-Term and issue ATSP3 to hard-set the OBDII protocol to ISO9141-4. To revert back to automatic detection enter ATSP0. This is assuming that your clone chip supports at least most of the Elm327 instruction set. It’s a hack, but it might get you connected.

Regards,

Joe Baumbach
Engineer
ScanTool.net, LLC
http://www.scantool.net

Thanks for the info, Joe. I'll try the ATSP3 command as you suggested and see if that lets me connect.

btw, do you know of a decent online reference to the AT commands for the ELM327 chipset?

thanks again,
JohnB

You can get the ELM 327 datasheet from ELM Electronics:

http://www.elmelectronics.com/DSheets/ELM327QS.pdf

Enjoy!

Joe

"Think OBDLink"