Aftermarket Taillight Wiring

I got a lucas style taillight
( app.infopia.com/Shop/Control/Product/fp/vpid/4808346/vpcsid/0 )
to replace my clunky brake light on the '82 kz1000m. The Lucas Light has two connector wires, red and black, coming out the back. The stock lights have three connector wires, red blue and black. And I can't seem to figure out the correct wiring for the new light.

All I can figure out is how to get the braking filament to lite when pressing/pulling the switches. I cant get the running filament to glow at the same time.... suggestions.

Some of the British bikes from years ago had positive grounds instead of what is used in most bikes and cars as negative ground.

If it was me I'd take the light assembly off the bike, go to a suitable workbench/table with an ohmeter and some masking tape with a good marking pen and after removing the tailight lens and continuity check the socket(s) and mark the wires accordingly as to what went where. Also having a 12 volt D.C. power supply helps too.

The FSM (Factory Shop Manual) is color coded so mixing and matching cannot be to bad.

squints wrote:

I got a lucas style taillight
( app.infopia.com/Shop/Control/Product/fp/vpid/4808346/vpcsid/0 )
to replace my clunky brake light on the '82 kz1000m. The Lucas Light has two connector wires, red and black, coming out the back. The stock lights have three connector wires, red blue and black. And I can't seem to figure out the correct wiring for the new light.

All I can figure out is how to get the braking filament to lite when pressing/pulling the switches. I cant get the running filament to glow at the same time.... suggestions.

Are you sure the new light is a dual filament lamp? If so, the case must be ground and each wire goes to a filament. If it's a single bulb, the black wire is ground and red is the filament.

You could go with Mfolks idea and take it off of the bike, and test it with an ohm meter. But if you dont have one....

You could run a couple of wires off of your battery and see if you can get both filaments to fire.

the ground might be the casing of the lamp, with the two wires going to the two different filaments, grounding back to the bike through the casing.

Ground the casing of the lamp to the negative terminal of your battery via a short piece of wire, then touch positive to either of the two wires coming off of the lamp and see what happens.

You are expected to make a ground by connecting the bulb holder to your bike's frame. The red and black wires are the hot leads for the running and brake light respectively. Put a bulb in (SAE 1157 usually) and connect the bulb holder to ground. Then touch the red and then the black wires to a battery 12VDC hot source and one will be brighter than the other meaning one had the bigger filament lit. The brighter is your brake light; connect to the BLUE wire from your harness pigtail and the dimmer light is the running light. Connect to the RED wire from your harness pigtail.

I'd take the cover off that lamp and eyeball the bulb to make SURE there are two filaments in it.... I am nervous that it might be a single filament bulb and that black wire might be ground. If so, touching the lamp case to ground and putting +12V on the black wire is going to blow a fuse.

You guys might be right that the goofballs who designed it assigned a black wire to a hot filament lead..... but I'd take a look at the bulb before I connected that wire to +12V.

yeah its a dual filament bulb alright... I got both to light up separately(cant remember the configuration), but not at the same time.
I'll try some of these and then report back.

wiredgeorge wrote:

You are expected to make a ground by connecting the bulb holder to your bike's frame.

I did try connecting the red to red and the black to blue (vice a versa after a failed attempt)and then I kept the ground wire attached to the stock assembly. It didnt work. Should that work just the same as making my own ground attached to the bulb housing?

squints wrote:

I got a lucas style taillight

In the 60's we owned MG's and Jaguars which are full of Lucas electricals.

In Britain, his prowess at electrical wiring earned him the title "Prince of Darkness".

I never went anyplace without a fuse in my pocket.....

AWESOME. I touched both the red and the black wires from the light to the positive terminal of the battery and touched the bulb casing to the negative terminal, and blamo, all lights, both filaments.

So whats the best way to make the ground lead. Any tips on how to connect a wire to the bulb casing.

...ORrrr is there a chance that the mounting bracket for the taillight will be good enough ?

Right. for anyone out there wondering, I've succeeded in mounting the taillight. All that was needed was a bit of wire to connect to ground, as indicated above. It finally occured to me (I'm a moron) to just solder a bit of wire to the bulb casing, then I wrapped it with electrical tape and bota-bing, we're in business.

Dont look half bad Id say. Really lightens (HA:woohoo: ) up the back end.