Testing brake light switch

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Scott in NM
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Testing brake light switch

Post by Scott in NM » Sun Dec 05, 2021 4:02 pm

I can test the horn switch by removing it, connecting a multimeter, and checking for continuity by pressing on the button on the bottom. Is there anything similar I can do to test the brake light switch? Imagine it is hydraulic pressure actuated but I don't want to just cram something down the hole to try and make contact.

Scott


parker007
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Re: Testing brake light switch

Post by parker007 » Sun Dec 05, 2021 4:08 pm

do on vehicle, have someone push pedal and see if it have continuity.

JMZ421
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Re: Testing brake light switch

Post by JMZ421 » Mon Dec 06, 2021 3:06 am

The switch is pressure activated and I made sure that I had a good pedal prior to checking my switch and obviously the light switch in the correct configuration. John

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YLG80
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Re: Testing brake light switch

Post by YLG80 » Mon Dec 06, 2021 3:48 am

You can test it with compressed air through a tap rubber gasket with a hole :wink: .
Or you introduce the round head of a toothpick in the tiny hole and you push to activate the switch behind the rubber membrane.
But if the membrane is very old, it could be damaged.

Here is how it is inside the switch:

Brake_Switch_drawing-cut1.jpg

The rubber membrane is in orange and the moving contact in blue.

If you damage the rubber membrane with a toothpick, that is a good thing.
Better to damage an aged membrane when the switch is not attached to the master cylinder...
Yves
Ford GPW 1943 - Louisville - DoD 12-7-43
serial 164794

Scott in NM
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Re: Testing brake light switch

Post by Scott in NM » Mon Dec 06, 2021 11:44 am

Removed old switch. Per a suggestion from another board took a dowel and gently applied pressure. could feel the membrane move and then stop. No continuity with my multimeter, new switch on order. Thanks guys.

Scott


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