1968 CB250 headlight loose cables

[bech]

The green beam is the neutral light. The red - outside the cluster - mimics the hi-beam.

Both dials are illuminated at once by a white light which is on when the headlight is on - L and H - or when the switch is at P.

I haven’t measured the voltage between the two loose wires yet but I have tried them insulated (everything worked except the headlight), attached together (nothing worked), attached the black/red to the headlight adjusting screw and the green to one of the screws holding the headlight rim (everything worked).

I’m trying to find out why it works like this and a proper way to connect it.

As far as I know the BB had a green neutral light also but not a yellow mimic for the blinkers nor a rev dial up to 12.

Happy new year.

[jensen]

Hi,

Then I'm wrong I guess, but measure the voltage between the wires and also compared to ground, with light on and off.

But from which model is this speedo ?, This was mounted on a bomber, but I'm sure this is not original. Anybody ?

Jensen

[e3steve]

The green beam is the neutral light. The red - outside the cluster - mimics the hi-beam.

Both dials are illuminated at once by a white light which is on when the headlight is on - L and H - or when the switch is at P.

I haven’t measured the voltage between the two loose wires yet but I have tried them insulated (everything worked except the headlight), attached together (nothing worked), attached the black/red to the headlight adjusting screw and the green to one of the screws holding the headlight rim (everything worked).

I’m trying to find out why it works like this and a proper way to connect it.

As far as I know the BB had a green neutral light also but not a yellow mimic for the blinkers nor a rev dial up to 12.

Happy new year.

Without a voltage measurement it's difficult to offer further advice. From reading your opening post I was under the impression that all was well with the lighting. So, let's take it one step at a time:

• 1. Ground the black/red, insulate the green -- what works/doesn't?
  2. Measure the voltage between ground (neg) and the green (pos) in different modes:
  • a) key off
    b) key on
    c) parking light only
    d) dipped beam
    e) hi-beam
    f) brake light

Let me know. G'luck mate!

[bech]

Here we go.

1. With black/red grounded and green insulated just the hi-beam mimic lamp lights on with the switch on L or H. Nothing else works.

2. Voltage between ground and green (pos):
a. key off: 0V
b. key on: 0V
c. park light: 0V
d. dip beam: 11.25V
e. hi-beam: 11.30V
f. rear brake light: 0V

3. With black/red connected to the hi-beam mimic lamp and green insulated the cluster ilumination and the mimics red and yellow works and again is voltage between green and ground just with dip and high beam.

4. With black/red connected to the hi-beam mimic lamp and the green attached at the headlight adjusting screw everything works.

[e3steve]

Well, Bech, from your readings it appears that the green wire is the headlight dip-switch (dimmer) supply. I have a CB250 wiring diagram somewhere on one of my 'retired' hard-drives, but I think it's also on this forum somewhere. I'll look it out.

In the meantime, try connecting the green to the centre-contact feed of the dimmer switch.

Sorry for the delayed response, btw!

[e3steve]

It's not a CB250, but a CB360 diagram (herewith). Assuming that Honda didn't change too much of the wiring colours between the 250/250/360, it may be of some help.

According to this diagram, blk/r is the feed from the lighting fuse to the 'HEADLIGHT CONTROL SWITCH' and the gn is 'GROUND'.

Inspect the source of each and establish whether they exit the harness tubing or if they are spliced into the Honda wiring with AM butt-splices, Scotchloks (those bloody horrible squeeze-together-with-pliers IDC [Insulation Displacing Contact] snap-cover wiretaps!), etc..

Questions:

• 1. How much of your wiring colouration resembles this diagram?
  2. Do the two anomalous wires that we're discussing appear to be OEM or added by a PO?
  3. How many fuses does your ol' beauty have?
  4. Does yours have a front brake light switch?

We'll get there.....

[e3steve]

......I don't know which series though! It looks like quite an early model, judging by the presence of a selenium rectifier and CB77-similar lights-on charge-boost circuitry.

EDIT: I retract that last phrase; it's not so much a 'charge-boost' circuit as a 'charge-attenuation' when the lights aren't selected, whereby the alternator's coil sets are in series, lights off, and switched into parallel -- thus raising the voltage -- lights on.

Does yours have the 'EMERGENCY SWITCH' (engine cutout)?