I updated my brakes a bit using a power booster and 2 bay master, the original brake light switch had 2 wires, the new one only has one. Was the original supplying power and ground, and the new just ground?

Mike

 I'm on a Lowwwww Budget

Both switches are simple single-pole on/off type switches.



On the 2 connection one, you could use it to supply power to the circuit or provide the ground (by connecting one side to ground)



On the single connection switch it can only provide ground since the other "connection" IS ground.



Having the switch be the "switched ground" is probably a better way to do it since you'll need to have 2 wires to the fixture (you don't have to rely on the fixture staying grounded)..... Just make sure that the fitting the switch is screwed into is grounded well to the chassis or better yet, the "system" ground.



Since cars have computers and other high current devices in them nowadays, manufacturers now have specific grounding points where components are grounded. This way you don't have to rely on every metal part of the car staying "bonded" with every other part to keep "stuff" working.





I am actually wanting to upgrade my brakes using a "split" system like it appears that you have done. I am planning to use a hydraulically boosted(instead of vacuum boosted) , double reservoir master cyl.



I'll stay with the drums though.















Regards,





Rick


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1955 F-600/272/E4OD// Disclaimer: No animals were injured while test driving my F-600 except the ones I ran over intentionally!

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Mike, do you want to save yourself some headaches?  Mount a toggle switch on your brake pedal support.  It's easy to do and they come with as many poles as you want.  Those hydraulic switches are crap, some brake fluids are incompatable and make them break, they don't switch until you create brake pressure, instead of coming on when you depress the pedal, and they aren't reliable.

There's a good reason all new cars use a mechanical brake switch, nothing works better or lasts longer.  Hope this helps.  Dave

Royal Oak, Michigan (Four miles north of Detroit, and 12 miles NORTH of Windsor, Canada).  That's right, we're north of Canada.

Ford 292 Y-Block major overhaul by simplyconnected

Mike:

If the one wire switch is screwed directly into the master cylinder, it is not a brake light switch, it is a switch for a brake warning light for when one half the system loses braking.  It will not work with your present wiring.  The car the master came from probably has a mechanical switch on the pedal arm like Dave says.

John - "The Hoosier Hurricane"

You can install a T fitting in one of your lines which will allow you to run the hydraulic switch. If you want a mechanical switch, try a '73 to '77 ford pickup application. $1.99 or $5.69 from Napa depending on the brand you choose. MPESL169SB or ECHSL169. I'm converting to one of these as a part of my rewire project.






Lawrenceville, GA

The switch is in the preportioning valve, and my reasearch says thats where the stock brake light switch was, I know I am missing the obvious, but if it's one wire, it's ground switching, and since the brake lights are not stand alone, I believe i need to switch the +. Since the pedals sink into the floor a manuel switch isn't that simplistic, especially since i have clutch and shift linkage all bunched up there. Sigh ! 50 years from the I am sure the brake lights will come on when you think about stopping.

Mike

 I'm on a Lowwwww Budget

The brake switch doesn't go to ground. You should have a hot wire on one pole of the switch. The other runs into the turn signal switch where it gets directed to the brake lights. The brake circuit is grounded at the light bulbs. I suppose it could be different on an older vehicle. I can say with certainty that on ford trucks from 1961 to 1977 that is the way the brake circuit works. I actually fitted a 73-77 turn switch assembly into my truck this past weekend in order to get the built in hazard flasher function. So it's fresh on my mind.


Lawrenceville, GA

Thanks for your help fellas !

I would say it's time to find a wiring diagram, just bought a shop manuel online.

Mike

 I'm on a Lowwwww Budget

Mike, that proportioning valve switch indicates a EMERGENCY condition.  If either the front or rear systems fail, the proportioning valve goes to one side, activating this switch.  It IS NOT for brake lights, as I had originally thought from your first post (you didn't say it was on your porportioning valve, so we took it as a M/C 'Stop Light' pressure switch).

Hoosier John is right about it not being a brake light switch.  Actually, it is indicating one of your brake line circuits has NO pressure.

This can happen when installing and bleeding your brakes.  The proportioning valve needs to operate 'in the middle' so to speak.  If it comes on during a rear bleed, simply bleed a little more out of the front, and the light will go off.

You got a new Shop Manual on line?  If that means you downloaded it, look at the section for your Brake Warning lights.  There you will find the type of switch you need for your proportioning valve.  If you are stuck using the new 1-wire, you can easilly use it to energize a relay coil, then offer a relay contact to your existing pair of wires.
Hope this helps.
-  Dave

Royal Oak, Michigan (Four miles north of Detroit, and 12 miles NORTH of Windsor, Canada).  That's right, we're north of Canada.

Ford 292 Y-Block major overhaul by simplyconnected

You didn't say what year car you have, but if its a 50's/60's car it most likely has the hydraulic two pole switch, mounted on the master cylinder or on the frame. The wires are power in, power out when the brake pedal is pushed. I don't see how a single pole switch will work.

54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ