Background to why a diode kit is necessaryIn order to simplify the wiring systems on many motorcycles (otherwise known as cost saving!), many manufacturers opt to install a simple dashboard indicator signal warning lamp which flashes when either the left or right turn signals are activated.
The simple circuit used to add the warning lamp effectively bridges the left and right indicator circuits. When the left indicator is on, the dashboard warning light is powered by the left indicator circuit as you’d expect, but it uses the right indicator circuit as its ground path. The same happens in reverse when the right indicators are turned on.
What this means is that a small amount of current will flow through the dashboard tell-tale light, into the opposite indicator circuit (the one that should be off) and hence through the front and rear indicator bulbs on that side. When conventional filament bulbs are installed this is not a problem since the current is small and filament bulbs require much more current before they light up.
A problem arises however when we upgrade a motorcycles indicator lights to use LEDs instead of the conventional bulbs. LEDs are much more efficient and use significantly less power which means that they turn on with only a small input current. So the small current flow through to the opposite indicators via the tell-tale light is sometimes enough to make the other indicators flash too. This results in all four indicators flashing (rather like having hazard warning lights fitted) when either direction indicators are turned on. Clearly that’s not very useful.
The simple solution
The simple solution is to remove the bulb from the dashboard indicator warning light. This isolates the left and right indicator circuits and so prevents the cross-talk between the two sides. As a temporary measure, this is a useful solution if only to diagnose and confirm the cause of the strange indicator behaviour when you have installed LED lights. As soon as the warning light bulb is removed the problem should disappear and normal indicator operation resume.
This isn’t a good long-term solution though as you to lose the reminder that you have left your turn signals on. It is also likely that your bike may fail its next MOT test if the tell-tale light is not working correctly. Hence a more permanent solution is required.
The proper solution using diodes
The best long term solution is to slightly rewire the dashboard indicator tell-tale light by using diodes to isolate the left ad right indicator circuits. (Diodes are small electrical components which only allow current to flow in one direction, a bit like a one way valve in plumbing).
There are two stages to the modification. The first part installs two diodes to isolate the left and right indicator power circuits, and the second part provides an alternative ground connection to the warning lamp.
Everything you need to complete this modification is included in the MatchlessClueless LED indicator diode kit and the following instructions will guide you through the installation.
This modification works the same irrespective of what type of LED indicator lights you have fitted, although obviously the MatchlessClueless LED indicator boards work the best. The modification will continue to work even if you later swap back to traditional filament bulbs, so there should be no reason to ever need to undo your handy-work.
Please have a good read through all of these instructions before you start.
Installation guide contents (click to jump to a particular section):
The tools you will needThe diode kit includes Scotchlok quick fit connectors which remove the need for any soldering; you don’t even need to strip the ends of the wires!
Therefore the only tools required to install the diode kit are a pair of wire cutters and some pliers to close the Scotchlok connectors.
What’s included in the kitThe various components included with the LED indicator diode kit are as follows:
- 1x Diode assembly and wires
- 1x Scotchlok solder-free splice connector
- 3x Scotchlok solder-free pigtail connectors
This is everything you will require to make the modifications to your bike’s wiring loom to correct the feed-back flashing issue.
Step 1 – Preparing to install
Installation of the diode modification requires access to the wires that come from the various warning lights on your motorcycles dashboard. Depending upon the make and model of your bike access may be more or less difficult. If your biek has a fairing or enclosed bodywork around the headlight then you might need to remove some or all of this first.
As with any electrical work it is safest to disconnect the battery before starting work to avoid causing any accidental short circuits. At the very least you should ensure that the ignition switch, lights and indicators are all turned off.
Step 2 – Making the cut
At the back of your motorbike’s dashboard, locate the two wires which are connected to the indicator warning light. Most of the warning lights will have a power supply and ground connection, but the indicator lamp is slightly different. Each of the two wires is both the supply and ground – they switch round depending upon whether the left or right indicators is turned on.
Cut these two wires using a pair of sharp wire cutters (there is no need to bare the ends). It is better to cut the wires nearer to the multi-way connector rather than close to the dashboard unit. One of the cut wires will be used to make a new ground connection (see the next step below), so give some careful consideration to where best to make the cut before actually cutting the wires. “Measure twice, cut once!” as the saying goes!
Step 3 – Making a new ground connection
One of the two wires coming from the dashboard warning lamp that you have just cut will be used to make a new ground connection for the bulb (the other will be connected to the diode wire in the next step). If you are using a standard filament bulb in the warning lamp then it doesn’t matter which you chose as bulbs are not polarity sensitive.
However if you have already replaced the warning bulb with a LED equivalent (or think you might do so in the future) then it is important to chose the correct wire as the ground. Unlike conventional bulbs, most LED units are polarity sensitive (the MatchlessClueless LED boards are some of the few to include special circuitry to make them operate the same with either polarity). If you can trace the wires through to the warning light bulb holder, the one that goes to the outside of the bulb (i.e. not to the pin on the bottom) should be used as the earth.
For modern Triumph Bonneville, SE, T100, Scrambler and Thruxton models please see the section below which describes the typical factory wiring colours to make this process even easier.
The easiest place to make a connection to a new ground from is the ground lead from one of the other dashboard warning lights. The main beam warning light is the most common connection to use. You could run a new ground cable to a suitable earth point on the frame or even all the way back to the negative battery terminal, but this is far more complicated and much less neat than tapping into one of the adjacent warning light’s ground wires.
A Scotchlok splice connector is provided for making this connection. There is no need to cut the ground wire that you are going to tap into as the Scotchlok connector automatically makes the electrical connection when it is closed around the wire. Slot the connector over the wire so that it runs through the block under the metal blade (but don’t close this down yet).
Then take the cut wire from the indicator warning light that is to become the new ground connection and insert it into the right side of the connector (looking from the open side) parallel to the other wire. Ensure that it is pushed firmly against the stop inside the connector block so that it is under the metal gate when it closes.
When you are sure that both wires are correctly positioned under the metal gate in the connector, this can then be closed up using a pair of pliers. It is worthwhile gently pinching it up to start with and rechecking the wires are correctly positioned still, before then squeezing it full closed. The plastic flap can then be closed over the metal gate to complete the new ground connection.
Step 4 – Connecting the diodes
Examine the diode wire supplied in the kit and you will see that there are three wires coming out of it – two wires at one end and a single wire at the other. The diodes are provided with long (greater than 15cm or 6″) wires attached to give maximum flexibility with installation. In most cases these can be significantly shortened to make the installation as neat as possible, but the extra length is there just in case you need it.The single wire from the diode connects to the remaining cut wire from the dashboard indicator warning light. The double wires from the other side of the diodes go to the other sides of the two cut cables coming from the main wiring loom. It doesn’t matter which way round these two wires are connected as both are wired the same inside the diode wire package.
These three connections can be easily made by using the supplied Scotchlok quick connect pigtail connectors. Again there is no need for soldering, or even for stripping the ends of the wires. The ends of the two wires to be joined and inserted into the connector and then this is closed using a pair of pliers.
Full detailed instructions for using the 3M Scotchlok connectors can be found here.
Triumph specific instructions
The following instructions provide some more specific and detailed guidance to the colours or the various wires that you need to cut and tap into for the modern Triumph range of motorcycles, including the Bonneville, SE, T100, Thruxton and Scrambler models. The colour coding of the wires seem to be fairly consistent, although please note that they may vary between models and production years from those described below. Please use this as a useful guide, but be aware that your bike may be different and consult the appropriate wiring diagrams if you are unsure.
One of the two wires that come from the dashboard indicator tell-tale light is green with a white stripe (green/white). This is the wire which will become the new ground connection for the indicator warning light and which will be spliced into the ground connection from the adjacent main beam warning light.
The colour of the other indicator warning light wire may be plain green, or else green with a red stripe (green/red). Some people have also described it as being green with an orange stripe (green/orange), but the orange and red may actually be different interpretations of the same colour. Please note that there may be several green/red (or green/orange) wires coming from the back of the dashboard, so make sure you get the one that comes from the indicator tell-tale light. This second wire will be connected to the single wire coming from the diodes.
The ground wire of the main bean warning light is usually black. This is the easiest and most convenient wire to splice the new indicator warning light ground connection into.
Conclusions and your comments
So that’s the installation complete and your new LED indicators hopefully ready to give you many years of bright service. If you have any problems then please do not hesitate to get in touch via email or using the contact page. Please make sure your email address is correct so I can get back to you.
I would also be glad to hear how you found the installation process, any problems you encountered or anything that wasn’t clear or missing from this installation guide. Please let me know how I can improve the guide by leaving me a reply via the comment form below. Also if you have any photos you’ve taken of your bike during or after the installation process, then please email them to me so that I can add them to the customer’s photo gallery.
Finally, please let me know whether your Triumph bike had the same colour-coding of the wiring as I described above. If it differed, please post a comment below with the correct colour-code for your bike. It would also be useful if you could include the year and model of your Triumph. Many thanks.[disclaimer]