73 340 duster. Oil and brake dash light question.

No. When functioning correctly, the brake light will only come on if there is a pressure loss in the braking system. On some models it will also illuminate if the parking brake is on.
The oil pressure light will light up any time there is no/low oil pressure- ie at startup, or if oil level is excessively low.
Power goes from the instrument cluster circuit board, through the bulb, and out to the oil pressure sensor- and when there is no pressure, through the sensor to ground and the bulb illuminates.
Make sure you have the correct sensor, there are 2 different kinds- one for a light or one for a gauge. The gauge sensor will not work with a light, and the light sensor will not work with a gauge.
Oil pressure sensor for a light:
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Oil pressure sensor for a gauge:
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