finding cable for a specific circuit

[stranger12]

Hi Guys,

I am not very good at electrics etc but I need to figure out a why to know the function of each cable.

For instance I want to know which of the 10/15 wires going all the way to the rear is for the brake light, I am happy to make a small cut and use multimeter , is it possible then to press the brake so the light then comes up and presumable the multimeter value changes to tell me that is the cable that I need ?

if so how do I connect the multimeter, negative to ? positive (red) to ?
should it be on V setting ?

Does the same apply to car?

Many thanks
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SV650 Red
R6 Red

[anthony_r6]

I would start by finding the wiring diagram to your bike first. It'll be colour-coordinated so you can see exactly which wire is what, and what colour it is.

Edit : to answer your question. I'd have it set to 20v and you press the red on the lead you want to check and earth the black on some bare metal.

I think rear brake lights are permanent lives. So if there is power, you should pick something up without having to press the brake light.
____________________
Ted : "Maybe he's agoraphobic."
Dougal : "Jack scared of fighting? I don't think so, Ted."

[stranger12]

thank you , can I connect the black to body of the car/bike or negative terminal ? sorry if this sound stupid.

I know with some cars they have different pulsation to distinguish between indicator or brake light etc so you may end up only having one wire which is carrying the signal for 2/3 different things, is that right ? can you check this using the above method ?
____________________
SV650 Red
R6 Red

[anthony_r6]

You can earth it off on bare metal, or the negative terminal.

As for the single wire/multi function thing, I've heard of it, but I'm not up on it. Again, I'd start with the manual and a wiring diagram. I imagine (though don't quote me) that if a wire can carry multiple signals then you should see an increase in voltage or a pattern (such as spikes when the indicators light up, then drop as they go off)
____________________
Ted : "Maybe he's agoraphobic."
Dougal : "Jack scared of fighting? I don't think so, Ted."

[uberkron]

Use a testlight. You wont ruin anything. Earth it on the body. Lets you see power. Meters will show stray current and miliamp leakage.
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i ride a zip 50 2smoke. It overtakes a hundred times a day.

[WD Forte]

[iooi]

[stranger12]

thanks all.
did sort out the issue using multimeter
____________________
SV650 Red
R6 Red