Essential programmable features to turn on for the elm327 for testing.
AT PP 01 SV 00 - HEADERS
AT PP 01 ON - HEADERS ON AT START UP
AT PP 02 SV 00 - ALLOW LONG MESSAGES
AT PP 02 ON - ALLOW LONG MESSAGES ON AT START UP
AT PP 0C SV 23 - 115200 BAUD
AT PP 0C ON - 115200 BAUD ON AT START UP
AT Z
If you need to return you ELM to normal, type AT PP FF OFF or if your in more serious trouble refer to pages 54 and 55 of the ELM327 manual.