New tail light!

So I put on one of those side tail light/license plate holders on my '82 XJ750 and was left with one wire (appears to just be a ground wire) and the flasher wires. I hooked up both wires from the new tail light to the old wires from the old tail light and it lit up when I turned the ignition on. No brake light however when rear or front brakes are applied.

Also the front flashers don't flash but stay solid. I'm horrible with electrical work so I figured this would be an easy enough task to help me learn, but my wiring from the previous owner is a mess and diagrams aren't helping with all the "new" connections.

I know you guys like photos around here so tomorrow I'll tear it apart and take some so you can see what I mean. In the meantime maybe someone can help me out with just my description alone.

 

Okay. So here you have the wires I found after taking my rear fender off. The 3 wires (Yellow, Blue/White, Black) connect with the 2 and only wires (Black, Black/Blue) coming from the taillight. Originally the Black/Yellow wire ran from that connector all the way to the original taillight at what appeared to just be a ground wire riveted to the base of the bulb socket. The other 4 wires (Black, and Green) are the flasher wires. So being that I am totally clueless when it comes to wiring and electrical work in general I am in need of some assistance if possible.

 

Black is ground
Green is one of the flashers
Chocolate brown is the other
(Both need to be grounded)

Black also goes to taillight.
One of the other 2 wires is the always on running light (when bike is on); the last one is brake light.
I'm at work and forget which is which..

 

Okay as for the wiring off the light assembly many are body mounted grounded lights. So the black wire may not be a ground but actually the brake wire. The Red could the running light. Just went through this with both a Sparto Light and a LED tail light as well. Just a possibility.

 

Thank you both I'm going to try it tomorrow after work. I'm also going to take a photo of the chaos in between my side panels so you guys can see what I have been dealing with electrically. Maybe it's just all noodles to me I don't know. Anyway the light is off of my '81 CB650 that I've been parting out and it worked fine with just the 2 wires tied into that electrical system. Brake light and light worked. Thanks again guys!

 

Based on what you responded you have a body grounded taillight assembly you are trying to use.

If you don't get a good ground by merely installing it, find a way to ground it to BIKE'S black ground wire. (Ie new nut and bolt or solder to assembly metal.)

 

Alright well I tried grounding them and nothing happened. I know my brake light switch is working as it has with my old brake light (also here). I took some more pictures just for the hell of it here, and here.

 

Like Metal Bob said, it sounds like you have a self grounding tail light. Most new ones are, as is mine. The light must have good contact when mounted to provide a ground. Since you said the tail light will operate, it leads me to believe it has a good ground.

Does the the new light have one bulb with dual filaments or does it have 2 individual bulbs? It sounds as though one of the filaments is bad or you have a bad bulb. Here is what you do to test them...

Of the 3 wires from the bike: black=ground, yellow & blue = tail & brake. I can't remember which color is which, also easy to test.

Disconnect all the wires and place the light somewhere with a good ground. Now, start with the yellow wire. Connect to 1 of the tail light wires. Does the tail light come on or does the brake light operate...make note. Then disconnect and reconnect the yellow wire the the other wire from the light. Does the tail light come on or does the brake light operate...make note. Disconnect the yellow wire. Then go through the same process with the blue wire from the bike.

By going through this process, you should be able to find which wire operates which function. Also, this will tell you if have a bad filament or bulb.

I hope this works. It worked for me, I had the same issues with my new light. Best of luck!

 

^^^^^
Also make sure the bike is running while trying to test the lights this way

- - - - - - -

Another way to test: Add a ground to your "new" light assembly. Connect that new ground to the battery ground and then test each of the 2 wires to the battery + to see if the "new" light/bulbs work...

 

Alright as soon as I get my new coils I'm going to get her running and try it out again. Thanks to you all!

 

Hirsuit Do you not have any fuses? From your pics the wiring is pooched pretty bad. Here is a link to a simplified/minimal wiring diagram someone made not sure who: http://www.currentobservations.us/image ... Series.jpg

 

Ha yeah its tucked (screwed onto the 1/4 ply) in next to the battery. I'm even considering just buying a new wiring harness for the bike. The guy that "wired" it up had probably 5-6 different types of connections for everything. I'm assuming when he ran out the rest was twisted and taped together. Thanks Waldo that site will come in handy. I can't even tell you how frustrating the diagrams from the Haynes are!

 

I give up...I've swapped bulbs, replaced bulbs (1157's), tried rewiring my old lamp back on and that doesn't work now.

I am left with the following wires; from the bike: Yellow, Blue/White, Black, (and the Dark Brown and Green wires for the blinkers); from the new taillight: Black and Black/Blue, I then added a Ground wire affixed to the metal body of where the light itself is attached.

So after messing with all the wires I found out that the Blue/White wire coming from the bike, when grounded, powers both the running filament and the stop filament in the bulb.

The Yellow coming from the bike seems to do nothing when both leads from the taillight are touching it (whether grounded or not, or whether all of the wires are touching together). The Black from the bike is definitely the ground and when connected to the new ground on the taillight it acts as it should. Allowing me to light the running/stop filament up when I touch the Blue/White wire coming from the bike with the leads from the taillight.

I am lost on the Haynes as it shows 2 bulbs for my taillight. A lot of my wiring was half-assed by the P.O. and I finally figured out what all of the wires from the headlight bucket and my non-working speedo are for. I tried to trace some wires back and they disappear.

So I give up, if there is anyone within reasonable distance that thinks they can come give me a hand I'll fill up your tank and get you a 6 pack.

 

Anyone?

 

The blue white is the always on (with key) wire.
Yellow is brake.
Black is ground every where on the bike.

If blue/white is powering both filaments you did someething wrong.

On new light, black MIGHT BE brake (2 filaments), black blue MIGHT BE running light.

Try grounding the new light with wire grounded to assembly and plug other end into one of the original bike black plugs (not the frame).

 

I'll give it a go. I'm going to make a short video for you as well so you can see if I'm doing anything right or wrong. Thanks again Metal_Bob.

 

Alright so "iwingameover" came up the other day and it was as easy as you guys all said so now I have my awesome new light hooked up properly and I can't wait for new turn signals. This forum is the sh!t and again thank you all especially "iwingameover".