Can't enter service mode '93 del Sol

Greetings!

I have a high mileage 1993 del Sol Si. I replaced the distributor and wish to set my timing (with very little prior experience). I have found videos giving me decent directions, but I have a stumbling point that no one addresses.

I have found the connector under the glove box that needs to be shorted to enter "service mode" to adjust the timing, and placed a copper wire across the pins. My check engine light does _not_ illuminate when I do this. When I try to adjust the distributor to set the timing, I feel that the engine is resisting me. I move the distributor and observe the rpms changing and the timing marks moving under the timing light, but then they move back within a few seconds. I surmise that I am not in service mode.

The connector I'm jumping across is a two pin gray doohickey inside a green rubber boot that seems to have no function other than to keep the gray connector from dangling where my passenger would kick it. There is also a similar three-pin gray doohicky in the same green rubber boot (that also has only two wires). I tried shorting across the second connector's pins, and the car behaved exactly the same.

Any tips? My guess is that one of the wires to the connector is broken somewhere, so I'm not completing a circuit. I don't know how to diagnose that. Is there another place to access the points I need to short to enter service mode to set my timing? Is there some sequence of events I might have missed (e.g. short the pins before starting the engine, or short the pins after the engine is hot, or something else)?

Ken