1971 duster

Let's look at the pdf diagram you posted. That may be corrected because it matches what is on the car.

The T-shaped two cavity connectorfor the headlight warning buzzer shows L7A, just like yours. L7A should have continuty to the headlight switch connector.
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To the left in the diagram is an angled connector showing yellow wires is for the map ignition switch light.
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So the service manual shows the wires correctly but incorrectly illustrates that as a 3 position connector.