My service manual  says to leave Test mode connetor connected on one page and disconnected on another page, when retrieving codes. Which is it? And, is the test mode connector thr blue one with only one wire on it?

You can follow the instructions on my website as they give the proper procedure.

 

www.surrealmirage.com/subaru/engine.html

 

To perform the read memory mode, you connect just the black connectors and do not connect the green T connectors.  If you want to perform the active diagnostic, you connect only the green T connectors.  If you want to clear the ECU memory, you connect both the green T & black connectors.