Before the dual master cylinders and related brake monitoring systems, there was nothing on the earlier cars of that nature. It was felt that if the pedal went to the floor, YOU KNEW there was a problem that needed immediate attention.
If one of the two brake fluid circuits failed, the car would still stop, just not as well or quickly. So the warning light for that situation was needed. To illuninate if one of the circuits had failed or had lost brake fluid.
For 1966 and earlier, if the orig instrument cluster did not have a "brake" warning light, to indicate that the parking brake was deployed, the lower carlines (Plymouth and Dodge) could have an accessory light near the parking brake handle. Run by a simple contact switch, which would turn the light on past the first 2-3 clicks of the pedal ratchet mechanism. If it also flashes, the better to get your attention as it was not in the driver's normal line of sight.
Seems like that starting in 1968, the instrument cluster "Brake" light served to both indicate that the parking brake was deployed AND as the warning light for brake fluid loss?
The operation of the Parking Brake Warning Light should be mentioned in the Factory Service Manual. Free download at
www.mymopar.com. Might also be mentioned in the sales literature documents in the "Library" at
www.hamtramck-historical.com, too. "Might need to manually input those addresses)
Enjoy!
CBODY67
