This is a method to display more light back there than the typical stock single tail and brake light by putting the turn signals to work as running and brake lights. A two-filament or two-wire fixture is required to do this. If you have a single wire coming out of your rear turn signal fixtures, there are ways to retrofit an 1157-type base into some of them. Truck stops and bike shops sell fixtures designated as “two-wire” which means they typically use an 1157 bulb with two filaments or the LED equivalent. The two wires are for filaments, the grounding is usually done via the case of the light where it mounts.

Note: If you are converting amber fixtures, many jurisdictions in the US do not allow for continuously-lit amber lights on the rear. Also, if you read through this and don’t understand the procedures and concepts discussed, please have a competent person or shop do this work for you. Rear lights and signals are critical for safety. Check your lights frequently to make sure they are functional, that kind of habit marks the seasoned driver and rider.

There are other ways to do this; trailer wiring converters can be purchased inexpensively. However, reviews note that some of the converters don’t pass full power through, resulting in dimmer lights. If the converter fails on a trip, if might be difficult to replace easily, since some use differing connection configurations.

This schematic uses 3 commonly available 5-terminal relays and full size wire all through so the lights are bright. I used a small size relay since they will be installed on a motorcycle. Relays with an 87a terminal are required for this circuit. If one fails on a trip and you don’t have a spare, most auto parts stores sell slightly larger relays that can be used.

Both of the images below will expand if clicked on.

Here’s the schematic… I did link to the original on Element Owner’s Club but it’s been bought by capitalists who make you sign in to see anything…


Here’s an annotated photo with all internal connections assembled, ready to be installed…either outside relay can work the left or right signals, just make sure that relay has the same side inputting and outputting.

This assembly only connects to the bright filament. The dim filament in the 2-wire fixture is not connected to this assembly, it can be connected directly to the tail circuit for running lights. The fixtures must be grounded as they normally would be. What the relays do is make it possible for the bright filament to act as both brake light and turn signal while the dim filament works as a running light.

For the circuits affected by the relay pack, it might be useful to use connections that allow for the wiring to be reverted to stock configuration. I used extensions with spade terminals gendered so that the relays can be removed and the original wiring plugged back together.

I ordered the relays from fellow Guzzi rider Dan Prunuske. His relays do not require the diodes pictured in the schematic. His page has dimensioned drawings of the relays he sells.

If you would like to mount the relays in plug-in bases, search for Bosch 3 334 045 00. Those bases interlock with each other so that a solid block of relay base can be made from them. This was Ben Mosley’s innovation, worth considering since it will make changing a relay much easier if one fails. The only drawback I can see is a larger size for the combined set, if available space is tight. They add about an inch to the depth. You can see photos of his install and the size of the base on the ADV thread he started.

Also, Ben has uploaded a video showing how the lights work after conversion and explaining his installation. He very kindly links back to this page. Thanks Ben, safe travels.

Carl Krall