Dash Oil and Brake Warning light - how are they triggered in the start function?

67Dart273 said
Very simple. The key switch only has 3 outputs. ACC is powered in the "ACC" and the "run" positions of the key That line powers stuff like radio, wipers, heater

The "run" position of the key powers things like the gauges, the warning lamps, the ignition system, and the VR and alternator field, and in newer models, smog devices under the hood. THAT "run" power goes DEAD when the key is twisted to start. That means the warning lights go dead during engine cranking

This isn’t the case. Your general knowledge of the system is good, however, when the car is ‘cranking’ the Brake light warning indicator will illuminate, this is to show you that the light and system is functioning properly. When released (now run position) the only thing that should illuminate the brake warning light is a pressure imbalance (from the pro valve or distribution block), if the e-brake is engaged, or if you have a faulty switch in either.

That said, I’m wondering what, in the start function, grounds the brake warning light, in order to show the temporary illumination and its proper functioning.

Also, there is no ‘charging’ light on these cars, just an ammeter.

Both the brake warning light and oil light have power at the circuit board in the dash in the run position all the time but will only illuminate when the prospective light’s switch is triggered (oil or brake) which does the triggering by means of Ground.