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Re: Brake light on the dash- help needed
Drum / drum systems still use split circuit designs and I believe most have a bias valve trip system built in...
I just checked my original factory 67 longbed I am working on and it has a proportioning valve like valve immediately under the master cylinder...with a switch built in...
I believe the valve in this scenario trips when a hydraulic circuit fails on either front or rear brakes.
A true proportioning valve is in a Disk / drum or disk / disk system to limit the pressure applied to the rear system to prevent lockups etc.
The alert switch is in these later style systems again to alert of hydraulic system leaks.
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