Connecting LED turn signals on your motorcycle

Modern LED (Light Emitting Diode) technology has opened up a whole new world of possibilities in turn signal design. Low power consumption takes a load off the electrical system, small-diameter cables reduce cost and save weight, the powerful light output allows tiny dimensions and imaginative designs, and long LED life saves you the bother of frequent replacement. Especially on a motorbike, small housings are a great bonus – a traditional "bulb" turn signal looks like a soup bowl compared to today's, street-legal LED mini turn signals.

So it's no wonder that many bikers decide to switch to stylish LED turn signals when an original turn signal needs to be changed and the dealer's price for the OEM spare part comes as quite a shock – if they haven't already made the switch, that is. 

In principle any bike with a 12 V DC electrical system can be fitted with LED turn signals. 

When you buy yourself new turn signals, always check that the lenses carry an "E" mark indicating that they are type-approved. All turn signals in the Louis range have a valid "E" mark. Approved "front" turn signals bear the code 1, 1a, 1b or 11, and approved "rear" turn signals bear the code 2, 2a, 2b or 12. Many turn signals in the Louis range are approved for both front and rear, so have two codes. Bar-end turn signals with an "E" mark are only approved for the front of your motorbike, and you must have rear turn signals in addition. If you have a choice of turn signals with stalks of different lengths, please bear the following in mind: under EU rules, front turn signals must be at least 240 mm apart, rear turn signals at least 180 mm.

We will now show you how to install LED turn signals with resistors on a Kawasaki Z750. The LED turn signals we are using are curved, which is why there is one model for front left and rear right and another for front right and rear left. 

Unfortunately, when you remove your original turn signals, you're left with unsightly holes almost big enough to throw the new mini turn signals through. This is where turn signal mount covers come in handy. These covers are not specifically designed for the Z750 but they are easy to adapt. If you cannot find anything suitable for your motorbike, you can make your own covers out of aluminium, plastic or sheet metal. 

In our example, we can use prefabricated adapter cables, which are available from the Louis range for many different motorbike models. They make it far easier to connect the new turn signals because they can be fitted directly to the compact connectors on the wiring harness. Likewise, the other connectors will fit the resistors and turn signals without any modification. If you are not able to use adapter cables, please refer to the instructions in Step 4.

1. As with all work on the bike's electrical system, the negative cable must first be disconnected from the battery to avoid a short-circuit. 
2. To replace the front turn signals, take off the front fairing and set it down in a safe place (on a cloth or blanket). 

Now you can remove the original turn signals and screw on the new ones including the mount covers. When tightening them, remember they are not truck wheel bolts, so don't use too much elbow grease 

Incidentally, mini turn signals often have a fine thread M10 x 1.25 (standard nuts are M10 x 1.5). So if you lose a nut underneath the workbench, please order a replacement. 

Next, connect up adapter and turn signal cables. LED turn signals will only work if the polarity is correct. As the motorcycle manufacturers do not use standardised cable colours, a circuit diagram, if available, is useful for localising the positive and negative cables. 

Proceed in the same way for the other side, and then you can put the fairing back on. The cross-head screws all engage in plastic threads, so take care when tightening them.

To fit the rear turn signals and resistors, take off the seat and unscrew the tail fairing. Once again, carefully set down this expensive and delicate piece of plastic. 

In the same was as for the front turn signals, now remove the rear turn signals and fit the new mini turn signals and mount covers. Route the cables in their original positions.

Now the resistors need to be installed on the rear turn signals. Do NOT connect them in series. They must be connected in parallel to give the correct flashing frequency. If you buy resistors from Louis, they come prewired in parallel (see the picture below). 

The resistors have no polarity, so it doesn't matter which way round you fit them. The cable terminals provided with the Louis resistors make for easy installation. 

The resistors can reach temperatures above 100° C when in operation (prolonged use of turn signals, or hazard warning flasher if you break down), so they need plenty of air to keep them cool. They should not be completely enclosed or mounted in direct contact with a plastic surface. So it's a good idea to make a small mounting plate out of sheet aluminium and place that in the bike. 

The Z750 has a metal plate on the right, next to the control unit, which is an ideal place to install it. This is where we fitted the resistor for the right turn-signal circuit using 3 mm nuts and bolts. We fitted the resistor for the left turn-signal circuit on the left side next to the control unit. However, the resistor cannot be screwed directly to the visible metal plate on this side, as there is another control unit underneath the plate, which could get damaged. So we screwed the resistor to a metal plate and then inserted the whole thing under the black box.

Once you have wired and connected the resistors (don't forget the battery earth cable), it's time for a test. We monitored the temperature of the resistors with an infrared thermometer. They heat up to almost 80°C in just a few minutes. 

So you should never use double-sided adhesive tape, for example, for securing the resistors in your fairing. It will not be strong enough, and may end up causing damage! Once everything is working correctly, you can refit the tail skirt. The conversion is now complete!