normally closed switch help here.

[brunop39]

Hello guys,
I am in great need of some help here.I am new here,,,have some electronic knowledge but its been years since I really worked on the actual field,,anyways here is the problem I have I am sure it will be simple for you guys that work with this more frequently than me..

My motorcycle brake switch is a normally closed switch,according to the digital meter testing I did. The thing is that only the running lights and the brake light works constantly always on..I am sure I have something wrong in the Main wiring harness,but don't even want to mess with it..I want to create a separate circuit out of the main wire harness so that I can activate the brake light filament only when I press the brakes in the bike. I cant change the switch to a normally open switch......I was thinking on using a regular automotive relay you know the ones that have the 85,86,87,87a and 30 pins don't know the name but its a relay,with a 30 amp fuse or smaller..there are 2 brake light filaments I need to activate....If anyone can give me a help making a diagram of some type I will gladly appreciated,,,,new here so an email with the help to brunop39@yahoo.com will do,,,,,thanks all in advance,,hope someone can help me here.
Bruno

 

[betwixt]

It sounds like there is something wrong with the actual switch but if you just want to reverse it's action by adding extra parts, you are basically right about how to do it.
Most automotive relays will do the job. They have connections to an activation coil and a switch that has one common connection which moves from one to the other of the switched connections. You need to wire the coil to where the lamp was and place the normally closed relay contacts in series with the new lamp wire. Wired like that, when the brake is NOT applied, the brake switch is closed and the relay energizes, that makes the contacts change to the normally open position and the lamp gets no power. When you operate the brake, the coil de-energizes and connection to the 'normally open' pin is made which cuts the lamp power. Basically, the relay works as a parallel switch but in the opposite sense.

Brian.

 

[brunop39]

Hello Brian,
Thanks for your quick reply and advise. I little confused here,sorry for my ignorance,,,,,can you just give me a simple pin connection layout? What I have looked in the internet as far as this relay is
Pin 85= + 12Volts input Coil
Pin 86= Ground output Coil
Pin 30 = Ground
Pin 87A= normally CLOSED OUTPUT
pIN 87= NORMALLY opened OUTPUT

What I need is examble connect pin 85 to 12 volt battery in series with fuse,,,or what ever......Looking for a 12 Volt output to energize only one filament I suppose I need a fuse since it will come out directly from the battery,if possible indicate what gauge wire I would need for this.. again thanks for all your time on this.
Bruno

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Brian what is confusing me here is that you state the lamp gets no power and on the next sentence you state cuts the lamp power,,,,hope you understand what I mean...
Bruno

 

[iimagine]

Another simple solution and cheap is using one transistor and a resistor, I dont know how much current your brake light need, so you need to measure or search and find out, then you can properly set the bias resistor and select a proper transistor, the circuit I am posting is using a simple LED for demonstration.