Going through the wiring for this engine swap(1991 model year). Several wires go to a "check connector" as referenced by the manual. Is this connector ever used? It's a 22 pin black connector. 

Edited August 22, 201510 yr by Speedwagon

I see it all the time in the wire diagrams but I've not seen any reference to using it for diagnosis. I think its only used for factory diagnosis when the car is built.

The important ones are the yellow 9 pin SSM plug, the 2 bright green and the 2 black single pin test plugs. On later models there is also a black 6 pin diagnostic plug used for testing ABS/TCS, Airbag, and TCU modules.

Thanks