Introduction to installing your new LED rear light unitThanks for purchasing one of our new LED rear light boards for Triumph Bonneville, Bonneville SE, T100, Thruxton and Scrambler models. These step-by-step instructions will guide you through the installation process and electrical connections for your bike.
If you haven’t already purchased a LED board, you can find more details on the Triumph Bonneville LED rear light board product page.Installation is very straightforward as the LED board screws straight into the original mounting holes in place of the original bulb and reflector unit.
There is no cutting, drilling, soldering or other modification of the rear lamp unit required. Everything you should need is included with the supplied mounting kit. Electrical connections are made with the new 3M solder-free connections.
Please have a good read through all of these instructions before you start. Installation time is normally between about 10 and 15 minutes.
Installation guide contents (click to jump to a particular section):
- The tools you will need
- What’s included in the kit
- Before you start…
- Step 1 – Removing the rear lens unit
- Step 2 – Removing the bulb and reflector
- Step 3 – Installing the mounting posts
- Step 4 – Making the electrical connections
- Step 5 – Installing the LED board onto the mounting posts
- Step 6 – Reassembling the rear light unit
- Conclusions and your comments
- Customer’s installation photo gallery
The tools you will need
Only a few simple tools are required to install your new LED light board:
- A suitable screwdriver to remove the two screws holding on the rear lens
- A 7mm spanner (or 7mm socket and wrench)
- A 2.5mm Allen (hex) key
- Wire cutters to disconnect the old bulb
- Pliers to close the solderless wiring connections
We can supply an optional installation tool kit comprised of the required 2.5mm Allen key and a 7mm combination spanner if you don’t already have these tools to hand.
What’s included in the kitThe various components included with the LED light board kit are as follows:
- 1x Triumph Bonneville LED light board
- 1x three-wire connector
- 3x 3M solder-free wiring connectors
- 2x 12mm mounting posts
- 2x 10mm mounting posts
- 4x M4 insulating washers
- 2x 16mm long Allen (hex) screws
- 2x M4 spring washers
Before you start…
Installation shouldn’t take long, but it’s worth having the bike positioned so that you can comfortably access the rear light unit, somewhere dry and with decent light to work by. A quick clean of the rear light unit is worthwhile before you start to avoid getting dirt and grime over your shiny new LED light board.
As with any electrical work, it is worth disconnecting the battery (or at least removing the appropriate fuse and ensuring the power and lights are all switched off) to avoid making any accidental short circuits. You might however need to confirm the electrical connections for the brake and tail light power supplies, so it’s perhaps easier to leave the battery connected until its time to wire in the new light unit. Check that the ignition and all light switches are turned off though.
Step 1 – Removing the rear lens unit
The red plastic lens of the Triumph rear light unit is held in place with two obvious screws which can easily be removed using a flat-bladed screwdriver.
Once the screws have been withdrawn, the lens can be removed from the lamp unit. It is worth giving it a good clean at this stage, especially inside where dust can accumulate in all of the ridges and grooves which make up the diffuser pattern. An old tooth brush and some soapy water come in handy.
The two screws can be discarded as two new stainless steel hexagon headed screws are included as part of the kit. (Keep the old screws safe somewhere though if you think you might ever wish to go back to the original bulb fitment as the new screws are shorter than the originals).
Note that the two screws shown in the photo above are not the original Triumph ones. These were missing from the rear light unit I used to prototype the LED boards and which is shown in the pictures on this page. The actual screws have a coarser thread as they screw directly into the plastic rear shell of the light, whereas the ones shown in the photo have a standard M4 thread.
Step 2 – Removing the bulb and reflectorNext, remove the bulb by gently pushing it inwards and rotating by a few degrees anti-clockwise in the normal bayonet fitment style.
The ‘reflector’ is the shiny-silvered plastic parabola which focusses the light of the standard filament bulb out through the red rear lens. This is required for a filament bulb as these emit light evenly in all directions, however it is not required for the LED upgrade since these already have a focussed light output.
The reflector can therefore be removed by pulling it outwards from the main lamp unit. With the red lens removed, it is only held on by friction and should therefore come away quite easily. Take care not to damage the two plastic mounting posts as these are where the new LED board will also attach.You will find that there are three wires going into the bulb holder on the rear side of the reflector. (Note that the colours will most likely be different to those shown in the photos in this guide). Gently ease the wiring out through the hole in the base of the lights rear shell so you have a few inches of play; you can leave the plastic reflector hanging by its wires as you ponder the next step.
There is no way to disconnect the wires from the bulb holder, so you will need to cut them with a pair of wire cutters or snips. But before you do, take note of which colours go where. You will notice that two of the wires go into the very end of the bulb holder; these are the power wires for the tail and brake light functions. The third wire goes to the side of the bulb holder underneath; this is the earth (or ground) connection for both circuits.
The tricky bit is determining which of the two power connections are for each of the brake and tail light functions. Some initial observations by customers on their own Triumph bikes suggest that the factory colour-coding is as follows:
- Black – the ground connection on the side
- Blue – the brake light power connector (on when you apply the brakes)
- Red – the tail light power connector (on when the side or head lights are switched on)
Note that these are currently only observations from a couple of modern Triumphs, but it is likely that they will be common across most models and recent years of bike.
You can double check the connections using a multimeter; an extra pair of hands would also be useful at this stage! Set the multimeter to read voltage and select the 20v range (or else the smallest range above 12v). Touch the black (negative) to a bare metal surface of the motorcycle frame or engine, or very carefully to the ground terminal on the side of the bulb holder in the rear of the reflector.
Next carefully touch the red (positive) probe to one of the two power connectors at the end of the bulb holder. If you look down the hole from where the bulb has been removed you should see the two circular contacts. By getting your assistant to turn on and off the side lights, and apply the brakes to activate the brake light, you should be able to deduce which of the two power wires that go into the end of the bulb holder relate to each of the light functions. The multimeter should read around 12v when the appropriate light is on, and zero when it is off.I would be grateful if you could let me know what you find (along with your year and model of bike) so that I can update these instructions as necessary for future customers. You can send me a message from here.
Once you are certain of your bikes particular colour code, make sure that the lights are all turned off again and preferably also disconnect the battery just to be sure of avoiding any accidental short circuits.
You can then cut the three wires allowing you to completely remove the reflector and bulb holder assembly. If you think you might wish to reinstall the original bulb holder at a later stage (perhaps if you were to sell the bike), then it is worth leaving a couple of inches of wire attached to the bulb holder to make reconnection easier. Otherwise cut the wires close to the bulb holder to give you as much length to play with as possible.
The reflector and bulb are not required for the LED light board upgrade. These can therefore be discarded, or else kept somewhere safe (along with the two original long lens screws) if you think you might wish to reinstall the original filament bulb setup at some point in the future.
Step 3 – Installing the mounting posts
With the reflector removed, you can now install the mounting posts that will position the LED light board within the rear light housing. There are four mounting posts supplied in the installation kit; two longer (12mm) posts and two shorter (10mm) posts.
Take the two longer (12mm) mounting posts and screw them by hand into the two plastic mounting posts in the rear shell of the light unit, as shown in the photo. The thread is the same as the two long mounting screws which we unscrewed in Step 1 to remove the red lens, therefore they should screw in easily. Take care not to cross or strip the thread in the plastic mounting posts.
Once fully screwed in by hand, the mounting posts can be carefully ‘nipped up’ a fraction of a turn using a 7mm spanner or socket. Again take care not to over-tighten or strip the thread in the plastic housing, especially if the rear lens has been removed a number of times in the past (for example, to change bulbs).If you find that the thread is lose as a result of repeated screwing and unscrewing of the fixings, then you might find that a few wraps of plumbers (PTFE) tape around the thread of the mounting posts before installing might tighten them up.
If your light is very worn, a last-resort option might be to apply a small amount or glue to the threads of the mounting posts to ensure they don’t work lose. Sadly the Triumph lamp housing isn’t the best design and the plastic threads are a weak point, but it should be fairly easy to get a satisfactory fit of the mounting posts in this way even for the most worn of light units.
Step 4 – Making the electrical connectionsThe LED light boards are supplied with the new ‘3M Scotchlok’ style connectors to make the wiring connections very easy. No special tools, no soldering, no temperamental bullet connectors and no tricky screw terminals are required! For conciseness in this instruction guide (and because the same connectors are used in some of our other products), a separate guide to using the 3M wiring connections is provided.
Note that the 3M connectors DO NOT require the insulation to be stripped back from the wires prior to insertion. If any of the wires from the bike or the LED board are stripped, cut the ends back so they are no longer bare.
The three wires from the LED board are colour-coded to match the typical Triumph factory colour-coding as described above, namely:
- Black – the ground (earth) negative connection
- Blue – the brake light positive power connector
- Red – the tail light positive power connector
Once the three wires from the LED board connector have been connected to the three wires from the bike using the supplied 3M connectors, the power adapter can then be plugged into the LED board. The three-pin connector is designed to be a snug fit to prevent it ever unintentionally coming lose, so care is required when inserting the plug so as not to damage the internal contacts.The best technique is to present the plug up to the connector on the LED board, then angle the tip down slightly so that the pins are hooked into their respective sockets. The plug can then be pushed gently home, levelling it back out as the pins go into the sockets.
If you find that any of the wires are pushed out the back of the plug by the pins on the LED board as it is pushed into place, remove the plug and push them back gently but firmly into place until you hear (or feel) a small click indicating they have locked into position.
Step 5 – Installing the LED board onto the mounting postsWe are now ready to install the LED light board onto the mounting posts in the rear light’s shell. Included in the installation kit are four plastic washers which will be fitted on either side of the LED board (front and back sides) to provide insulation, and also to help stop the mounting posts vibrating lose. Put an insulating washer onto each of the two short (10mm) mounting posts, then push the mounting posts into the front of the LED board. Put the other plastic washers onto the mounting posts on the rear side of the LED board so that the board is sandwiched between the two sets of plastic washers.
The LED board can then be offered up to the rear light unit and screwed into place by hand. Feed any lose wire back into the shell of the light behind the LED board.Once the outer (short) mounting posts have been screwed into the inner (long) mounting posts by hand, they can be nipped up using a 7mm spanner or socket. Again, take care not to over-tighten the posts so as not to damage the plastic mounting of the lamp unit. A second 7mm spanner is useful to hold the rear mounting posts stationary whilst tightening the outer ones into them (or a spanner on the rear and a socket on the front will also work).
With the LED board secured in place you can now reconnect the battery and test the tail and brake light functions. Double check that the brake light comes on when the brakes are applied, and the tail light functions (including the number plates and side position lights) come on when the headlights (and sidelights) are turned on. If the functions are reversed then you have most probably got the two power wires (the blue and red ones) connected to the bike’s wring the wrong way round.
Step 6 – Reassembling the rear light unitThe final step is to reassemble the rear lens unit. The original long slot-headed screws are replaced by two shorter stainless steel hex (Allen) headed screws. The two M4 spring washers go onto the hex screws first to provide vibration resistance. Replace the red plastic rear lens and screw the two hex screws (with the spring washers fitted) into place using a 2.5mm Allen key. Double check that all of the wires are tucked behind the LED board so that they do not get trapped between the lens and rear shell of the light as you tighten the screws.
Also check that the rubber sealing strip which runs around the edge of the light’s shell is correctly seated so that the red lens compresses it into place. This provides the weather seal (waterproofing) for the light unit so it is important to check it is correctly in place, squeezed between the shell and lens of the light unit.
Tighten the screws sufficiently to compress the spring washers, but do not over-tighten. Inserting the long end of the Allen key into the screws and turning the shorter end by hand should provide about the required tightness.
And that’s it – installation of your new Triumph LED rear light upgrade is complete. Stand back and admire your handy work!
Conclusions and your comments
So that’s the installation complete and your new LED rear light board ready to give you many years of bright service. If you have any problems them 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, I would like to repeat my earlier request for you to let me know whether your bike had the same colour-coding of the wiring for the rear light 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.
Customer’s installation photo gallery
Here are a few photos of the installation process sent in by previous customers who have fitted one of our new LED boards to their own modern Triumphs. Hopefully these help to show how the above instruction work in practice, and just how simple and quick the installation process actually is!