ERA Dash Differences - Warning Light

[mr0077]

Bob,

My #598 has a S/C instrument panel layout, and has a red light above the key that (according to the wiring diagram) is a brake warning light; to my recollection, it has never come on. A friend with #644 has the same light in a street panel layout, but his operates like an alternator warning light (lights up when key is turned on, goes out when engine starts, comes back on if engine dies, etc.), and he has nothing wired to the brakes.

First question, how does my light work (under what conditions)?...it looks like it will light up when one of the master cylinders bottoms out.

Second question, was this a running change between 598 and 644 or was the light function different between the street and the S/C dash layouts?

[strictlypersonl]

The change was made around #635 to both the SC and Street dash layouts. It was done because we could no longer get reliable brake switches suitable for the warning light. They work by comparing the pressure in the front and rear hydraulic circuits. If there is pressure in one end without pressure in the other, the light will come on. I felt that wasn't something especially critical since you'd be able to tell something was wrong by the pedal height.

Currently, when there's a failure of an old style switch, I replace it with a two-terminal one that won't work with the dash warning light circuit.