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Discussion Starter · #1 ·
After my power supply issues I'm going to install a digital volt meter which also has a clock function. My question is where can I take power, earth and switched isnition feeds from and can anyone give wire colours if known?

Cheers 馃榿
 

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2008 YZF-R125 (180cc)
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Installing a voltmeter is a great idea since it gives you instant feedback on the state of the bike before you even hit start. I have one of those little digital ones stuck to the fairing stay in front of the steering neck...that way I see it when I'm about to start the bike but it doesn't annoy me while riding.

*btw this all applies to gen1, i don't have a gen 2 or 3 so they might be a little different, though probably similar.

I would have thought your best option for taking power would be from the ignition bundle which is just inside where the frame spars meet before the neck. So you'll need to take the fuel tank off and then underneath that you'll find a red square connector which disappears round the right side of the neck to the ignition key. I think that connector has 3 terminals and one of the 2 red/reddish ones will be the source/permanent power to the ignition barrel and the other one will be switched power coming back to the ecu or whatever from the ignition barrel. Obvs tap the switched one. Use a multimeter to test and see which it is before tapping anything. You can stick the multimeter prongs into the back of the plug where the cables go in (aka "backprobing"), with the ignition etc still connected.With ignition off you'll see 0v, with it on you'll see 12. You can use any nearby black cable/terminal or the frame itself (bare metal only, not paint) as a negative for the multimeter.

*obvs your voltmeter is basically a multimeter so in this case you can just use that if you don't have a regular multimeter.

I took my power feed from the "ignition barrel"-side of that plug/wiring since that's replaceable and so i wouldn't have to mess with the loom, and then ran that positive to a bullet connector inside the right side of the fairing where the headlight cables go, and from there I was able to run a few small items - my voltmeter, power for the coolant temp gauge, and also take a signal voltage to a relay to switch my heated grips on and off with the ignition. That cable will have a fuse on it so if you plug a high load item like heated grips directly into that, you will blow the fuse and the bike won't start, but gauges and stuff use hardly any power..

For ground/earth/negative I don't remember quite what i did and have just put the bike back together so am not in a hurry to take it apart and check, but there might have been a ground lead on the ignition plug or might have taken a connection from somewhere else.I just checked on a spare loom and there look to be 3 wires going into that red plug, so presumably permanent +, switched + and -. You can use the multimeter to see if you get a 12v reading across the positive ones and the third cable then that's negative and is fine to use. I guess ideally use a Tee or piggyback connector and tap the wire a little way up from the plug, then wrap the join with insulation tape or self amalgamating tape to make sure no moisture can get in. Ideally stagger the joins by an inch or two so that the cable bundle doesn't get super chunky for that section.

I took the individual connectors out and soldered my cable to the terminal which was a pain in the ass to do and actually not as good an ideas as it seemed - but I was trying to avoid any damage to the cable.

The frame itself is earthed/negative so normally you have more options a negative lead - you could happily run the positive lead to your voltmeter and just have the negative of the voltmeter attached to the bare metal of the frame if you wanted, but there's likely a negative cable (usually black or sometimes brown) which you can take a lead from somewhere nearby more easily.

If you're unsure whether you've got the right cable for a negative, before you cut into it you can either stick a pin in the back of a plug terminal that cable connects to (and attach the wire to that) to test the connection, or at a push the pin thru the insulation of the wire itself, though generally I try not to damage the insulation at all since with time+heat any damage will become a crack as the insulation dries out over the years which then may cause electrical issues. (old VWs with 30 year old wiring looms back this up).

Hope that helps :)
 

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Discussion Starter · #3 ·
Installing a voltmeter is a great idea since it gives you instant feedback on the state of the bike before you even hit start. I have one of those little digital ones stuck to the fairing stay in front of the steering neck...that way I see it when I'm about to start the bike but it doesn't annoy me while riding.

*btw this all applies to gen1, i don't have a gen 2 or 3 so they might be a little different, though probably similar.

I would have thought your best option for taking power would be from the ignition bundle which is just inside where the frame spars meet before the neck. So you'll need to take the fuel tank off and then underneath that you'll find a red square connector which disappears round the right side of the neck to the ignition key. I think that connector has 3 terminals and one of the 2 red/reddish ones will be the source/permanent power to the ignition barrel and the other one will be switched power coming back to the ecu or whatever from the ignition barrel. Obvs tap the switched one. Use a multimeter to test and see which it is before tapping anything. You can stick the multimeter prongs into the back of the plug where the cables go in (aka "backprobing"), with the ignition etc still connected.With ignition off you'll see 0v, with it on you'll see 12. You can use any nearby black cable/terminal or the frame itself (bare metal only, not paint) as a negative for the multimeter.

*obvs your voltmeter is basically a multimeter so in this case you can just use that if you don't have a regular multimeter.

I took my power feed from the "ignition barrel"-side of that plug/wiring since that's replaceable and so i wouldn't have to mess with the loom, and then ran that positive to a bullet connector inside the right side of the fairing where the headlight cables go, and from there I was able to run a few small items - my voltmeter, power for the coolant temp gauge, and also take a signal voltage to a relay to switch my heated grips on and off with the ignition. That cable will have a fuse on it so if you plug a high load item like heated grips directly into that, you will blow the fuse and the bike won't start, but gauges and stuff use hardly any power..

For ground/earth/negative I don't remember quite what i did and have just put the bike back together so am not in a hurry to take it apart and check, but there might have been a ground lead on the ignition plug or might have taken a connection from somewhere else.I just checked on a spare loom and there look to be 3 wires going into that red plug, so presumably permanent +, switched + and -. You can use the multimeter to see if you get a 12v reading across the positive ones and the third cable then that's negative and is fine to use. I guess ideally use a Tee or piggyback connector and tap the wire a little way up from the plug, then wrap the join with insulation tape or self amalgamating tape to make sure no moisture can get in. Ideally stagger the joins by an inch or two so that the cable bundle doesn't get super chunky for that section.

I took the individual connectors out and soldered my cable to the terminal which was a pain in the ass to do and actually not as good an ideas as it seemed - but I was trying to avoid any damage to the cable.

The frame itself is earthed/negative so normally you have more options a negative lead - you could happily run the positive lead to your voltmeter and just have the negative of the voltmeter attached to the bare metal of the frame if you wanted, but there's likely a negative cable (usually black or sometimes brown) which you can take a lead from somewhere nearby more easily.

If you're unsure whether you've got the right cable for a negative, before you cut into it you can either stick a pin in the back of a plug terminal that cable connects to (and attach the wire to that) to test the connection, or at a push the pin thru the insulation of the wire itself, though generally I try not to damage the insulation at all since with time+heat any damage will become a crack as the insulation dries out over the years which then may cause electrical issues. (old VWs with 30 year old wiring looms back this up).

Hope that helps :)
Thanks for the really comprehensive guide! Like you I don't like to touch the looms on vehicles and prefer to take supplies from removable parts to maintain the integrity,.as you say you can replace those but swapping out a loom is a pita.

Thanks again..really appreciate the help there. I'll take some pics as I go and post here should anyone else come across the thread...standby!

Cheers 馃憤
 
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