1938 stop light switch

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sslaugh711
Posts: 35
Joined: Thu Dec 15, 2011 10:49 am

1938 stop light switch

Post by sslaugh711 » Mon Apr 23, 2012 8:08 am

Brakes lights not working with new switch, I can hold the two wires that go into the switch together and the brakes light works. Brakes are new and work great. fluid shoots out when I apply the pedal when the switch is out. replaced the washer around the master cylinder cap for good tight fit, no fluid leaks out. What am I missing. Is there a good way to by pass or put another type of switch in? thanks Steve

Dave Czirr
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Location: New Jersey

Re: 1938 stop light switch

Post by Dave Czirr » Mon Apr 23, 2012 8:31 am

Steve, the only explanation I can see is that you got a defective switch. Was it a NEW SL-134 from NAPA or equivalent. Those switches have extreme reliability, probably more so that most anything else electrical in the car. Are you using silicone brake fluid? - it's know to drastically shorten the life of those switches, though certainly not to the extent you're reporting - more like failure in months or a year or two. Have you bled the brake system thoroughly?

That switch was used on just about every make of American car and truck for many years, they are only about $12 or so, you might want to pick up another on the remote chance you got a bad switch. No alternative type of switch is going to be more reliable.

sslaugh711
Posts: 35
Joined: Thu Dec 15, 2011 10:49 am

Re: 1938 stop light switch

Post by sslaugh711 » Mon Apr 23, 2012 9:40 am

I bought a switch from Max Merrit, didn't work then got one from Napa today, doesn't work either. Have not bleed the brakes since they work so well. Will try that this weekend. thanks

Adam
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Joined: Fri Sep 04, 2009 4:15 am
Location: lincolnshire, uk

Re: 1938 stop light switch

Post by Adam » Tue Apr 24, 2012 5:05 am

I think you should rebleed the brakes. (Which may only need to be done at the mastercylinder banjo fitting). If fluid shot out when pressing the pedal with the switch removed, air will have gone in when the pedal was released, to take the place of the fluid. This air pocket may well prevent sufficient pressure rise to activate the switch when you press the pedal now. Especially if the air is filling the switch itself.

Just a thought.

Adam..
"Do not underestimate the English cousin.....they are not as stupid as they look!" - Signor Altabani in The Italian Job.

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