Brake Light Switch Question

[BobB]

This should be a really quick one for you experienced folk. I've searched the forum and read the shop manual to no avail.

My truck was "rigged" by a PO with a contact switch mounted to the under side of the floor pan. Messed that up when I removed the floor pieces to restore/protect them from rust.

I have the original switch (currently unused) on the forward end of the master cylinder that I want to use to move back toward original equipment.

Here's my question: If my old switch is bad, does replacing the brake light switch on the master cylinder require releasing pressure in the master or even bleeding the lines?

I'd rather avoid a big surprise. Thanks so much for your help.

Bob

[Merle Coggins]

If you have the new one ready and swap them fairly quickly you won't loose much, if any, fluid. And you shouldn't need to rebleed the brakes.

Merle

[BobB]

Great. Thanks so much! Just didn't want a geyser...

Bob

[TodFitch]

If you have the new one ready and swap them fairly quickly you won't loose much, if any, fluid. And you shouldn't need to rebleed the brakes.

Merle

 

+1

 

Been there, done that. And I did not need to rebleed afterwards.

[desoto1939]

Put a piece of wood againt the back of the brake pedal and wedge ino to the floor board.  This wil lprecent the brake pedal from pushing down

[BobB]

Do I need to do anything to the threads - Teflon tape or putty like would be used for other types of plumbing?

Thanks for your help

[desoto1939]

No just screw the hydraulic switch into the break block where all the brake lines join up.  Put the block of wood under the brake pedal as I said before and no fluid will be lost.

 

Rich Hartung

[Jerry Roberts]

I have a different opinion on those threads . The threads are probably a tapered pipe thread and I would seal them with teflon tape . 

[Bradley S.]

I've changed that switch twice now.  I always carry a spare.  It is indeed a tapered pipe thread and I prefer pipe thread sealant, but teflon tape works too.

[BobB]

Thanks, guys.

I propped up the pedal, wrapped the new one with a bit of Teflon and didn't lose a single drop of fluid.

Done and done. Many thanks. Bob

[greg g]

As a follow up, you might want to consider repowering the switch with a dedicated fused wire.  You just make up a line with an inline fuse holder I used 12 gauge wire. and a 15 amp fuse.  Powered it from the battery side of the starter main cable (or any handy hot with ign off source) ran it directly to one of the brake switch terminals. taped of the original power wire and abandoned it in place.

[deathbound]

As a follow up, you might want to consider repowering the switch with a dedicated fused wire.  You just make up a line with an inline fuse holder I used 12 gauge wire. and a 15 amp fuse.  Powered it from the battery side of the starter main cable (or any handy hot with ign off source) ran it directly to one of the brake switch terminals. taped of the original power wire and abandoned it in place.

 

Such a great idea and every time I read it, I tell myself I have to do it. Maybe this summer.....