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Brake Light Switch

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M

mudd

Senior Member
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hello all,

got a problem with brake light not working all the time, cleaned the connections to the fuses in the fuse box in eng compartment, seemed to help 25% but still having a problem with brake lights not working all the time

is their a brake switch under the car someplace,? i looked under the dash at the brake arm there but did not see one, and checked elect wiring diagram, i see a switch but no idea where its at

thnaks
 
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Re: break light not working bj8 ? switch someplace?

Follow the line from the master cylinder down to a four way brass fitting , the switch is screwed onto the top of this fitting connected to two wires by push on fittings.
 
Re: break light not working bj8 ? switch someplace?

You can also find your horns and then look just to your left and located on the frame support is the four way fitting and the brake switch.
 
Re: break light not working bj8 ? switch someplace?

Most likely the problem is the switch PCullen and Keoke reference, it's not the most reliable. It's a combination fluid/electrial switch. The replacement aftermarket switches are just as unreliable. I belive the problem in the switch is the fluid not providing enough pressure to activate the switch when it should. Some people, myself included, have bypassed that switch and installed a mechanical switch.
 
Re: break light not working bj8 ? switch someplace?

I replaced the original hydraulic brake pressure switch with an adjustable mechanical switch after the original and a succession of available replacements failed. The argument given by the mechanical switch seller (Watson's Streetworks, https://www.watsons-streetworks.com) is that in pressure switches the contacts do not "wipe" each other as they close, they just touch. This allows the contact surfaces to oxidize and they don't work as well as when new. I know the replacement pressure switches from Moss didn't last very long.
I've had the mechanical switch installed since November 2006 and almost 40K miles and have had no problems at all with it. It's kind of expensive, at around $28 (including shipping) when I bought mine, but it is very well made. Ooof! I see that the switch is now 40 bucks. I don't know if it includes that relay-looking thing shown in the photo at their website. I just got the switch.

With the mechanical switch, you leave the pressure switch in place in the hydraulic manifold to seal the fluid, then disconnect the wires and run them to the mechanical switch. Of course, you have to make up extensions for the wiring.
 

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Re: break light not working bj8 ? switch someplace?

I installed the same switch from Watsons-streetworks. As great as that switch is, it most likely will have a wear problem down the road.

Someone pointed out that my breaklights were not working. Narrowed the issue to the watson's switch. Opened the switch up to find that the brass plate the switch lever rides across had been worn down and a groove was made. The lever that made the groove therefore would not make the entire travel needed. I ground the brass plates smooth to rid it of the groove and it fixed the problem. Will I have to open it up again sometime later to do the same? I feel there must be a better mousetrap switch made by someone else, but who?
 
Re: break light not working bj8 ? switch someplace?

I want to know what "break lights" are .
Are they some kind of flashlight/disco ball lights used by "break dancers"
Do I use "break lights " with " break disks":congratulatory::playful::playful::glee:
 
Re: break light not working bj8 ? switch someplace?

Break lights are brake lights when they're broken.:wink:
 
Re: break light not working bj8 ? switch someplace?

I want to know what "break lights" are

Break lights are Brake lights cuz they gonna break.---:wink-new:

When mine quit working i got ticked off threw the switch up against a brick wall had no spare so had to put it back in. N it ain't quit workin since.-:applause:
 
Re: break light not working bj8 ? switch someplace?

OP-
A common test for the brake switch is to remove the two wires carefully and connect them electrically (paper clip, wire, needle nose pliers, etc). If the brake lights come on, then you know all the electrical stuff is working, meaning that the switch is the culprit.

The wires that attach to the switch have female spade fittings, and the switch has male spades. In removing my wires, the male spade part actually broke off from the switch instead of the two parts of the connector coming apart. So that was a hassle I didn't need, but perhaps you can avoid the same fate by removing your connectors more carefully.

Because of the low quality hydraulic switches sold these days, some have installed an additional relay which carries all the current. Dave Dubois discusses this on his website and even sells the relay circuits for a fair cost.

https://userwebs.donobi.net/sufuelpumps/othertecharticles.html
 
Re: break light not working bj8 ? switch someplace?

I installed a Watson brake switch on my Mark 2 Jag, and it worked quite nicely. The current owner, who did a lot of upgrading on that car, including getting rid of the points in the fuel pump, told me he had retained the Watson. You can adjust it so that you get brake lights immediately or a bit later. But fitting the switch is the challenge. Does anyone have a photo of a good Watson installation? One of the features of this change is that you don't remove the existing hydraulic switch, meaning you can simply reconnect its wires to restore its function. I believe Steve G has an alternative and probably less expensive switch conversion on his very interesting Web site.
 
Re: break light not working bj8 ? switch someplace?

Hi Steve,

Can you explain how you installed your snap switch? Im trying to sort out how to fix my brake light which is going on and off intermittently. More off than on....!

Thanks very much,

Chris Smith
 
Re: break light not working bj8 ? switch someplace?

Htimsc said:
Hi Steve,

Can you explain how you installed your snap switch? Im trying to sort out how to fix my brake light which is going on and off intermittently. More off than on....!

Thanks very much,

Chris Smith
Click to expand...

Hi Chris,
Click through the pictures starting here. These pictures show the switch and the mount I made for it. Your mount would have to be such that the switch is kept depressed by the brake MC clevis until you put your foot on the pedal. Whether you use this or the Watson switch, your mount must be adjustable. On the Watson, you adjust the arm:

https://www.pbase.com/stevegerow/image/70570841
 
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