72 Charger proportioning valve/brake light

[72 charger]

Since I have had my car (72 charger) on the road the brake light has always been on on the dash. The car has front disc and rear drum brakes. When I was doing my "resto" I sourced a used proportioning valve from Desert valley auto. My brakes all work fine but I'm not sure how to get rid of the brake light on the dash. Obviously if I unplug the sensor on the valve it goes off. I was looking at some diagrams and service procedures in my service manual but it says the valve itself is not serviceable just the switch. Wondering if there's something I can do like try and re bleed the brakes? Thought I read that maybe if there's a pressure difference between front and rear lines it will trigger the sensor. Figured I would check here before I go crazy reading all the service manual. Thanks in advance.

 

[R/T Boy 67]

Those valves are generally self centering, but it could be stuck over to one side. I guess the switch could be faulty, and shorted to ground. The pressure differential valve can be taken apart and cleaned, or replaced if necessary.

 

[steve340]

On the earlier cars this light was also operated/lighted by the parking brake switch.
Is that operating correctly?

 

[T2R9]

Did you perhaps use a LED bulb for it? I pulled my hair out trying to figure out why mine was on all the time. Turned out LEDs will pick up even a minuet amount of a circuit. Changed to a normal bulb and poof gone.

 

[72 charger]

Did you perhaps use a LED bulb for it? I pulled my hair out trying to figure out why mine was on all the time. Turned out LEDs will pick up even a minuet amount of a circuit. Changed to a normal bulb and poof gone.

Original filament bulb. But that is good to know I plan to keep everything on the car standard lamps.

 

[72 charger]

On the earlier cars this light was also operated/lighted by the parking brake switch.
Is that operating correctly?

I did notice this in my service manual. I haven't checked that for sure but I'm assuming since when I unplug the proportioning valve sensor it goes out.

 

[72 charger]

Those valves are generally self centering, but it could be stuck over to one side. I guess the switch could be faulty, and shorted to ground. The pressure differential valve can be taken apart and cleaned, or replaced if necessary.

I'll have to post the illustration from my service manual I'm wondering if its stuck or the pressure difference is keeping it off centered but I don't notice anything in the brakes when driving. I should take the switch out and test it.

 

[steve340]

I am pretty sure that switch goes to ground to get the light to operate. If you remove it you may get a fluid leak - some of them have an o ring seal.
Easy to test that switch in place - either an ohm meter or test light.
I your case it would be grounded at all times to give your fault.
If no ground at the brake switch it may be the park brake causing a problem.

 

[R/T Boy 67]

It is possible that the switch is just doing it's job, but the pedal would have a lot of travel, and you didn't mention that.