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Discussion Starter #1
G-day to everybody,

I know, that a lot of themes already cover this topic, however on a quick look up I have not found any similar issues/solutions for my situation.

Long story short - installed an aux fuse box via relay on my '04 wee. Used v-strom.co.uk article as guide (cannot attach due to post count).

However when I turn my key, no voltage is observed on the fuse box. Switched ignition live is taken from number plate wire (tapped into it), right next to the connectors.

Resistance of the relay - 35 and 75 ohm (I have two)
Current in the wire - approx. 0.3 A

I believe it is not enough to power the relay? Or what could be the problem here? Maybe I have taken the wrong wire? I would appreciate any knowledge share on this topic.

Thanks

P.S. On running engine the voltage does not appear as well.
 

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Discussion Starter #2
Also not to confuse on the current value, the measurement was taken before tapping into wire.
 

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well, I have checked some potential failure points and it seems that I have tapped into wire that leads to 5w bulb, which is license plate lighting.

should I re-tap into the wire before it gets distributed in parallel connection to tail light, blinkers and license plate?
 

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Confused about your power measurement: how did you measure the 0.3A exactly? Is this the current going through the relay to switch it and hold it? 4W seems high, should be half that or less.
When you tap into the 12V wire, make sure it is before the light bulb. Do you measure 12V while the tail light is on? Then it is correct. What about ground, where do you get it from?
 

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Discussion Starter #5
Confused about your power measurement: how did you measure the 0.3A exactly? Is this the current going through the relay to switch it and hold it? 4W seems high, should be half that or less.
When you tap into the 12V wire, make sure it is before the light bulb. Do you measure 12V while the tail light is on? Then it is correct. What about ground, where do you get it from?
I used crimping as a method for wire splitting, therefore I had to cut the wire first. After the cut I put my measurement tool in line with wires and taken the current reading, which was 0.3 A. Then I installed the relay.

I have used two ways of relay install. The first was wrong by purpose, but that made the voltage to the fuse box. The way of connecting was just to put relay terminals 85 and 86 in between the cut. On ignition terminals 30 and 87 connected, which was good. However the bulb of license plate was really dim.

Therefore I re-attached the relay, by splitting the license plate lightning wire. Connected terminal 86 towards the split, terminal 85 goes to battery (-) for test purpose. Connected terminal 30 to battery (+) and terminal 87 to (+) of a fuse box. After ignition there is no voltage on the fuse box, however the license plate light is glowing as always.

As another point I might have failed - I did not check what wire I have tapped into (+ or -), just took one before the connector which allows to de-attach the license lighting. But as option #1 has worked, I believe it should be the correct one?

Otherwise it would be good if anybody could share some pictures on how their setup looks like.

Thanks.
 

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124, if you are getting power on the wire to your light with the key on but no power at the end of the wire you have going to your relay, I would bet your tap connection is bad. I installed my aux fuse box the same way except I cut the wire going to the tail light and soldered in connections. I've personally just never trusted taps whereas a soldered connection is permanent.
 

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Discussion Starter #8
124, if you are getting power on the wire to your light with the key on but no power at the end of the wire you have going to your relay, I would bet your tap connection is bad. I installed my aux fuse box the same way except I cut the wire going to the tail light and soldered in connections. I've personally just never trusted taps whereas a soldered connection is permanent.
Due to lack of time I could not finish all the measurements, however I can say that the connection is pretty solid. I believe the issue is in the wire I have selected, as current in license plate wire is smaller than in tail light wire (according to wattage of bulbs). That sums up to the relay connection, which is also connected in parallel, and if my physics knowledge is not wrong, a really small current is going through the relay, which does not allow to close the 30/87 contacts together for voltage to appear on fuse box.
 

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Discussion Starter #9
124, I don't have photos of mine but this site might be helpful Relay Installation - LDRiders[/url]
Also I did not mention it in the initial post, but I used a crimp in order to split the wire. Mostly all done as in the article.
 

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Have you wired the relay coil in series with your rear light bulb? I am wondering if this is so. Make a sketch of your wiring diagram, upload it to a sharing site and post the link so we can understand what you are trying to do.

Here is an example how the wiring should be done:
In fact I have connected the relay coil both in series and parallel as described above.

Once it was in series, the relay connected 30/87 pins and the voltage appeared on the aux fuse box, but the license plate lighting was really dim.

Once it is in parallel (as per link), the voltage does not appear on the aux fuse box (pins 30/87 do not connect), but the license plate lightning glows as usual.

I believe the current is quite low in the license plate lightning wire and when it gets split to relay by a parallel connection it just does not provide a current strong enough to activate the relay. I assume I have to use the wire before it is split to rear light/blinkers/etc.
 

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Discussion Starter #12
In order to make things more clear. I have split the wire marked with red arrow, that is going to 5W license plate bulb. I have connected relay to it both in series (wrong) and in parallel (correct), however on parallel connection there is no voltage on the aux fuse box.

Should the wire split be near the yellow arrow?
 

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Measure the resistance over the two switched relay contacts (87 and 30). There should be conductivity, means almost no resistance when the ignition is turned on. If you have no multimeter rig up a 12V bulb or test light and attach to the battery direct via those 2 contacts. If there is no conductivity hook up the coil (85 and 86) directly to the battery + and -. If there is still no conductivity, the relay does not work.
 

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In order to make things more clear. I have split the wire marked with red arrow, that is going to 5W license plate bulb. I have connected relay to it both in series (wrong) and in parallel (correct), however on parallel connection there is no voltage on the aux fuse box.

Should the wire split be near the yellow arrow?
Hi, so it’s a little more clear now what’s going on. When you measured the current where you cut into the wire, you measured just the light bulb’s power consumption. 0.3A makes sense for a 5W bulb. Putting the relay in series is, as you now know, the wrong way because now you are sharing the 12V supply in series with a light bulb, and neither gets a full 12V. The relay probably gets the lion share because of its higher resistance, which is why it works, whereas the bulb is very dim. At least you know the relay itself works and is not defective.
My main suggestion is to focus on voltage going forward, not currents. Besides you can easily fry your multimeter and all kinds of fuses or even cables with current measurements (which are basically shorts between leads), if you are not sure which cable carries what voltage.
You need a solid ground reference. For measurement purposes, just use any bare metal on the bike such as a galvanized screw head and touch it with the black lead of your multimeter. Now connect the red lead to the connection you made on the tail light. Ignition on should illuminate the tail light and give you twelve volts (more or less) on the reading. This way you will know that the tap you made is good and at the right place. Now you will have to find the ground to hook up the other side of the relay. Where does the tail light get it’s ground? Are there three or two cables? If there are three one will be ground and you can use it and also splice into this one. Make sure you have twelve Volts between the two connections when the ignition is on, and zero otherwise.
I hope this helps. Sorry if I mention things that you already know.
 

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Discussion Starter #16
well, so a small update to the situation, as today i have had enough time to check all the wires and the previous setup. apparently i had cut into the wrong wire, which caused all the trouble. therefore a conclusion - do not be hasty and re-check everything twice.

big thanks to all involved. appreciate the help and advises.
 
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