Two Stoplight Switches???

unit91 · 07-14-2008, 02:58 PM

I haveswitches on the brake pedal andon top of the master cylinder. What's the one on top of the master cylinder for?

Starfury · 07-14-2008, 03:19 PM

On top of the m/c? There shouldn't be anything on top of the m/c except the zinc-coated cap. There is, however, a switch on top of the distribution block. That's part of the pressure differential switch for the brakes; it lights up the dash brake light if one side of the brake system loses pressure.

kalli · 07-14-2008, 06:15 PM

64 1/2 mustangs have the brakelight switch on top of the master cylinder. maybe you got one of those?
disconnect the cable there and see if your brakelights still work/. Then you'll know which of the switches is used

Starfury · 07-14-2008, 07:20 PM

looks like a 67/68 in the pic, though. Don't know why anyone would put a single-bowl m/c in one.

unit91 · 07-14-2008, 08:30 PM

OK. My bad. It's a 68 Mustang, and it has a dual bowl master cylinder with two lines coming out of it. The switch is on one of those lines, not the top of the master cylinder. Sorry. So what have I got there?

kalli · 07-15-2008, 03:57 AM

make a picture sure.
They only ideas that come to my head are:
stoplightswitch, brake warning as Tad says and low brakefluid level warning.

Kalli

Starfury · 07-15-2008, 11:18 AM

On one of the lines? Or on the brass block on the fender?

unit91 · 07-15-2008, 09:52 PM

On the line that's closest to the firewall.

jlg2002 · 07-16-2008, 02:18 PM

That switch is the for the Inst panel "Brake" warning ight that comes on when the shuttle in the distribution block senses there is unequalized brake pressure. But I don't see that circuit on a 68. It looks to start in the 69 model year. Is the switch wired?

unit91 · 07-22-2008, 01:20 PM

Yes, it's wired. The switch is round, has two prongs on the top, and the wires go thru the firewall into the interrior.