This tells me the EEC is for a manual mustang. Still, i'd find it and runthe numbers to confirm. On the Mustang, there is a harness that connects to the top of the transmission to indicate neutral, as well as to the clutch pedal. usually to run the codes requires the clutch to be pressed in, and the trans in nuetral. Who knows if this was wired correctly in this case. This is rumored to cause idle surge issues, but hasn't been confirmed. Worth investigating how this circuit was plumbed up.