Wire/plug coming off my drum brake proportioning block?

[Luke87gt]

Hi guys, can someone give me a summary of what the plug/wire is that’s coming off my brake proportioning block (4-wheel drum)?

I will be converting to front disk soon and I don’t recall the new proportioning blocks I’m looking at as having a place for a plug/wire…

Thank you,

Luke

[Rust_never_sleeps]

It's the switch that trips the brake light on the gauge cluster when pressure in the front or back circuit drops and the differential pressure valve moves off center

All combination valves have them top center, AFAIK

[Rust_never_sleeps]

https://mpbrakes.com/tech-combination-valve/

[Richard]

Originally Posted by Luke87gt

Hi guys, can someone give me a summary of what the plug/wire is that’s coming off my brake proportioning block (4-wheel drum)?

I will be converting to drum soon an I don’t recall the new proportioning blocks I’m looking at as having a place for a plug/wire…

Thank you,

Luke

Your post is confusing to me? You have 4 wheel drum and converting to drum? What switch does is already mentioned. Many aftermarket prop valves for disk/drum will just have a pressure switch that enables brake lights. It does not operate the same as stock.

[Luke87gt]

Originally Posted by Richard

Your post is confusing to me? You have 4 wheel drum and converting to drum? What switch does is already mentioned. Many aftermarket prop valves for disk/drum will just have a pressure switch that enables brake lights. It does not operate the same as stock.

Whoops meant front disk conversion. Typing too fast late last night.

Thanks for catching that

[Luke87gt]

Originally Posted by Rust_never_sleeps

It's the switch that trips the brake light on the gauge cluster when pressure in the front or back circuit drops and the differential pressure valve moves off center

All combination valves have them top center, AFAIK

Perfect, thank you!

[Sheepdip]

Also, just so you know, that wire is a "Grounding" wire for that particular dash light. If you
un-plug it and ground it out, the light should come on. When your brake fluid system malfunctions, it pushes to one side or the other and grounds out to light it.

[Rust_never_sleeps]

FTR, when you get your new MC+Combo valve, put the little pluggy thingy into that same socket until you're done bleeding.

Wait to swap in the switch until you're sure you're done so that differential pressure slide can't move, impede flow, and generally p1ss you off

[PbFut]

Rust is correct. If you are unfamiliar with these systems, they are very simple, and easy to learn. But....If you miss a step or don't understand the valve that trips the switch connected to the wire you are asking about, as Rust says, you will go nuts for days trying to "fix" or trace what you did wrong. Lots of posts on the subject, as it's easy to get caught is the shuttle valve trap.