Topic: Rear Running Light Issue

[DennyK]

Folks,
I am writing to see if anyone has a similar experience.  My bike is a 1974 CB750 that we restored.  The bike spent some time in California and some PO converted the rear turn signals so they could be used as running lights.  The brown wire was simply spliced into and the rear signal sockets were converted to dual contacts.  We did replace the wiring harness; cleaned up the connection to the brown wire and installed new aftermarket handlebar controls (right and left) from Vintage CB750. 

The right side control has an ON and OFF setting that in the ON position lights the running lights.  My problem is that the right side rear light is touchy; by that I mean when the right side switch is in the ON position it also seems to light the yellow turn signal indicator bulb on the dash and that cancels out the right rear running light.  When I wiggle the turn signal switch I can find a place where the yellow turn signal light goes out and the running light will come on.  Also during this, I am not activating the flasher.

I did write to Vintage CB750 and they have not heard of such a problem.  I am running 1034 bulbs in both rear lights.  When the right side switch is in the OFF position things work however the running lights are off.  Even then when using the turn signals it is still a bit of a “hunt” to find the off position after I make my turn.  By the way if I put the ignition switch in “park” both rear lights shine bright. 

Just looking to see if anyone else has experienced this, or ideas to make this work better.

[Mr. Mike]

"Ideas to make it work better"

I'll take that to mean you're ok with running lights as well as blinkers on the rear.
The simplest way, which I did to my 78 CB750 was to;
1) round up a second set of front blinkers as they're dual contact base.
2) spliced the running light leads into the tail lamp.
3) hooked up the blinkers as original.
Not too complicated.

I wouldn't think the rear lamps would be bright on park, maybe the brake lamp filament is being used. I would double check the new harness connection points for color to color consistencies. The online diagram shows blue for right blinker, orange for left and brown for tail light.
All else fails, disconnect the rear wiring addons and check for proper signal, brake, park operation.

[DennyK]

Mr. Mike,
Thanks.  I think I am set up just as you described.  I included a picture to help show that.  The brown wire comes into the junction and from there it continues on to the tail light and gives power to two leads going to the rear turn signals.  The other leads that go to the turn signals can be seen wrapped in pink shrink tubing.  Now when I disconnected the two leads at the junction, the turn signals did not work.  I put the two bare leads together and the bulbs lit, but were weak. 

In your set up, do the running lights burn one of the filaments while the turn signals use the other?  In my set up, only one of the filaments is being used.

[Bodi]

If you want the rears to work just like the fronts, you need to get the wires to the front marker lights to the rear signals (light blue/white, orange/white). The markers turn off when the signal is used, I don't think those marker wires exist at the rear on a stock harness.
They should use both filaments, "dim" for marker and "bright" for signal. Without some electronics I don't know any way to use one filament as signal and marker.
Check that amber rear running lights are legal if that's your plan.

[DennyK]

Bodi,

Thanks, I wonder if I simply put the wires that are in the shrink tape into the junction and just plug the other two wires together. I need to check the front signals to be sure that both filaments are being used. 

[DennyK]

I just checked the front and both filaments are being used.  One for the TS and the other for the running light.

[Mr. Mike]

Yes
In my set up, I used OEM front blinkers and as described, I simply used the blinker wires as originally used, but you have to make sure they're lighting the proper filament, so a small bit of testing is required to get the proper wires before you make your splice permanent. In your picture, it's hard to tell, but you should have a color tagged wire (orange one side left, blue the other-right) and the wire from the tail lamp. The ground is provided when you fasten the blinker stem back onto the frame. The brighter of the two filaments is the blinker. If you already have factory signals on the rear, the color codes or tags should be as described and located just forward of what you picture shows with bullit connectors joining them to the harness. Do you indeed have dual filament lamp bases?

[BobbyR]

Not to be  downer. Amber running lights are not legal in any State since it is a DOT regulation.  They secify red in the rear only. The idea is for you to know the front from the back so you can tell the direction of travel.

[DennyK]

Mr. Mike,
So I do believe I have dual filament bases, in that there are two contact points in the bottom of each base.  That said, I do have the turn signals working and that uses the brighter filament.  I am thinking of connecting the wires from the harness to the two leads that are now in the 4 way junction and then put the other two leads in the 4 way.  I will use some plug in connectors so that it can be easily undone if need be.  My front turn signals are new aftermarket and work properly.  I did not compare the bulb bases and the ones in the rear are the ones that were on the bike when I got it. 

To Bobby R, thanks for safety DOT tip.  I will look into replacement parts to make the bike legal and hopefully more visible.

[BobbyR]

You can have all the red lights on the back you want.

[Mr. Mike]

Hi Bobby-

Yes I've known that and have modded two reds just in case. Same on my HD, the amber pops out visually rather than a sea of red at a stop, so I chance a ticket every time I ride. So far I've been fortunate on both. Thanks for being informative on the subject.