Quote: the headlamp warning buzzer in the above wiring diagram I posted is what I am also wondering about.
It's the grey female 2 way connector - seen below top left. Approx. a foot above the bulkhead connector or approx. 6 inches above the turn signal and ignition steering column wiring connectors. The diagram shows installed w/ male 'diode.' This isn't the key in buzzer harness connector previously seen in a few of the other pics already posted earlier.
Was this connector used for anything as the diagram suggests, or a late decision to not use and make the key in buzzer also the headlamp warning buzzer?
OK here's the story on that connector... ...The connector is obviously part of the main harness as you can see...It's purpose is to bring the key-in buzzer circuit{Q13-18R) and the headlight switch circuit{L6-18BK/Y*} together in the same location....On cars without the A01 light group it is simply an unused connector...But the on the cars with the A01 or the headlight delay that connector gets a factory installed diode to bridge the connector in a way that the current from the headlight switch will activate the now double duty key-in buzzer....The diode itself in this case is simply a blocking diode where the current will pass through it from the headlight switch but will not allow the current from the key-in switch to backfeed to the headlight switch circuit...So that leads us to the main objective.... If you want your key in buzzer switch to perform the double duty of the headlight warning buzzer you need to install a diode bridging that connector... ...
...The connector is obviously part of the main harness as you can see...It's purpose is to bring the key-in buzzer circuit{Q13-18R) and the headlight switch circuit{L6-18BK/Y*} together in the same location....On cars without the A01 light group it is simply an unused connector...But the on the cars with the A01 or the headlight delay that connector gets a factory installed diode to bridge the connector in a way that the current from the headlight switch will activate the now double duty key-in buzzer....The diode itself in this case is simply a blocking diode where the current will pass through it from the headlight switch but will not allow the current from the key-in switch to backfeed to the headlight switch circuit...So that leads us to the main objective.... If you want your key in buzzer switch to perform the double duty of the headlight warning buzzer you need to install a diode bridging that connector... 
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