Topic: Tail and Guage Light Wiring

[turkey4me]

I have seen a few posts on this subject but never could find the answers to my lighting issues, hope someone can help.

76 CB 750F
Speedo/Tach lights are not working. 
Using a multimeter could get no power from brown/white wire feeding into headlight bucket.  Traced this wire back to ignition and still had no power in off, run or park position.

Tail light only works when key is turned to park.
Have brake lights but no tail light when key is turned to run and bike is running.

At my aftermarket ignition switch there are the following wires:
Black only has power at Run setting
Red always has power
Red jumper always has power
Brown only power in park
Brown/White no power in off, run or park

Seems to me the Brown/White should have power in the run position and the brown should have power in both run and park?

none of my 3 fuses are blown.

Would appreciate any help...

[cookindaddy]

I just put mine back together yesterday so its pretty fresh in my mind and I just re-looked at the schematic.

I believe you are correct to be expecting power on the brown/white wire at the switch when in the RUN position.

Take the plug off the switch and look at the contacts? Clean, shiny and well formed? I know that I had some problems with mine and replaced one of the blades in the housing. With the plug off the switch, check the switch continuity in the RUN position from the red wire tab to the brown/white wire tab?

[turkey4me]

In the run position, I do have continuity at ignition switch from red lead to brown/white and also to brown.  All connections are clean and secure.  Sounds like my problems are from somewhere else?  Any ideas?

[cookindaddy]

Sure. Try checking the continuity of the brown/white wire from the ignition switch to where it comes out in the headlight bucket. Clean out and look at that (brown/white) multi connector carefully. Pull the three brown/white plugs out of it and clean it. Polish each one with a bit of fine steel wool if they look oxidized. If that checks okay. Put the plug back on the ignition switch and check for voltage at the brown/white in the headlight bucket with the ignition in RUN. I know that you said you did that before, but let's check again. What are you using for ground for your meter? I found that the headlight mounting studs are quite handy inside the bucket and both should have green wires running to them.

If you get voltage on the brown/white now to a good frame ground and the bulbs in the instruments still don't light, it's time to 1) check the bulbs in the gauges and their wiring and 2) check their green wires that should also go to one of the green multiconnectors in the headlight bucket. You can check their continuity to frame ground with the ignition switch in the OFF position of course.

[turkey4me]

I am still trying to figure out the reason behind why I don't have tail or guage lights.  If any electrical geniuses out there could take a look at a wiring diagram for a 76 CB750F I would appreciate some help.

When in the run position I have continuity across my ignition switch from brown to brown/white.  According to the wiring diagram there is no connection to power here so it makes sense I am not getting voltage. 

I also have continuity from the brown tail light wire to the front brown wire and to the fuse box.  When in run position I also have continuity from rear brown tail light wire to front brown/white guage light wires.

Here is the strange thing I can't figure out, in the run position, I have no voltage coming to the left side of the tail light fuse.  I can only get power here when I turn the key to park.

Anyone know where the power should be coming from?

[TwoTired]

The Honda wire diagram shows a jumper from the TL1 terminal to the PA terminal on the ignition switch.

In the headlight bucket (I think that's where it is, I don't have you specific bike) there is a jumper from Black to Br/B that powers the tail fuse and the run lights.