73 340 duster. Oil and brake dash light question.

[flathead31coupe]

I have tested both light bulbs in the - for the brake light and the oil pressure light.
They are both good. Doesn't
both lights come on on the dash when you go to start the car... Then go out once the car is running? What would cause this not to happen?Car runs fine.... And starts good.

 

[Professor Fate]

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:

Oil pressure sensor for a gauge:

 

[flathead31coupe]

I have the first one that is what's in it now... I was just thinking that if you turned the key on and did not start it.Those 2 lights would light up, and once it started They would go out unless there was an issue....

 

[Oldmanmopar]

Brake light will not light unless the park brake is pulled or brake failure. The oil light should light with the key on and not running. Ground the wire going to the sender on the block and the oil light should be lit with the key on. If not you have a wiring issue.

 

[flathead31coupe]

Thanks

 

[flathead31coupe]

I found out what it was.The - light bulb holder had one of the tabs broke.Wasn't making a good connection.
It's fixed and working thanks