The TEST-ONE will make troubleshooting this vehicle easier, it will show all available inputs that come in through the canbus wires (tach, handbrake, doors, brake, etc...)
Without a test-one, one input at time will need to turned off on the bypass options table and hardwired to test which input is causing the issue.
That being said, since this is a manual transmission vehicle, a professional shop/installer shoucl be consulted to verify functionality of the system to prevent errors that may cause the vehicle to start in gear.