Headlight circuit issue

Hello,
It's been a while since I've posted-the last time was my successful Ninja 500 regulator/rectifier on my -74 Z1
Many thanks to all the great help, much appreciated.
I ride my bike quite a bit,and last night I had to tape my iPhone to the headlight to get home 
Spent over an hr trying to figure out what was wrong but it was 2AM and I took the backroads, got home fine.  Phone light just there so people could see me, roads are well lit and I could see ok-
The ground on the headlight socket/solder was coming off, but I re spliced it right there, still no juice.  I had just converted to the H4 setup a few months ago.  Connected the headlight direct to batt with 2 wires, tested both low and high beam, works like it should.  So the H4 headlight bulb is not burned.

So today I started going through the wiring.  The problem with this bike is when I got it, it came with an aftermarket throttle.  No right switch.  So no on/off for the headlight, no kill and start switch.  The Start switch is a push button, and the lights are normally on with the left switch controlling high and low beam as it is with the stock setup.  My blinker switch and blinkers work.  So even after the headlight shut off, blinkers, tail and brake lights all still work.  I took the left switch apart, sprayed cleaner etc.  Blinker part of switch works, headlight doesn't and I couldn't get any juice when I connected my volt meter.  The blue wire ground has continuity.  Then I went to the red/ black and red/ yellow wires that attach to the headlight socket.  Nothing.  Where the left switch has the connector with 6 wires, on the main harness side I'm not getting 12v, so it looks like the left switch high/low beam is ok, but not getting 12V from the harness to it.  

So where the previous owner deleted the right hand switch with headlight on/off, those wires should be connected since I can see the tail and brake lights working.  They should be Brown Blue and Red to have the lights go on. So I'll have to find out where the wires are spliced together from when the previous owner deleted the right hand switch.
But I keep thinking, the tail light is on, brake light also works.  Could the fault be on the ignition switch then?  Is the tail/brake independent from the headlight wiring? It sort of is, since the left switch controls low and high beam.  Service manual shows a separate diagram for testing tail/brake system.

I'll also look through my splices from when I put in the EX500 Regulator/rectifier unit.  It's been woking so good, it sucks something like this just happened
www.kzrider.com/forum/4-electrical/61018...namo-stator?start=24

Main fuse is ok-I switched to a modern fuse, the old box is still there with the other fuses and I think it has nothing to do with this gremlin.  Pulled the main fuse off, no tail and instrument lights.  Plugged back in and all works except headlight.

So it could be that I'm overlooking something that's so obvious I'm just too irritated to notice.  I'll have some time tomorrow afternoon to use the volt meter and check again.  I'll follow the Service manual's procedure to check the ignition switch and the left hand switch.  So it looks like power doesn't reach the low/high part of the switch, while the blinker part works(my horn is deleted)

Any ideas much appreciated
Thanks
JB

We've seen conductors break inside the insulation where it can't be seen in the area of the steering neck.  Repetitive flexing when the forks are turned full lock is the cause.  It sometimes presents as an intermittent failure of whatever circuit is affected.  Can be a PITA to troubleshoot.  A conductor broken inside of otherwise sound insulation can often be detected by manipulating the individual wires with the circuit powered on or, with a meter connected set to continuity.

 Sometimes a broken conductor can be found by flexing the wire and simply watching how the insulation bends.  A sound conductor will flex in a smooth curve.  A broken conductor will create a much sharper bend in the insulation at the point where the conductor is broken inside the insulation.

Good Ridin'
slmjim & Z1BEBE

Could it be that the fault is in the ignition switch and it won't send power to the headlight?  I'll put my voltmeter on it and see what I get.
As mentioned, all other lights are working.  When I cracked the bike on the way home, headlight just stopped working.  The socket had come loose on previous occasions and I just slipped it back on.  This time it's probably the wire that brings power in, where in the left handlebar you can select high or low beam.
I', pretty sure in the flurry of testing everything I tried seeing if the high/low wires on that switch were getting 12 volts but I believe it wasn't, I'll have to re-test. But hard to believe both the red/yellow and red black would have broken connectors.  I'm thinking 12 v is not reaching the dimmer switch, though it is reaching the blinker switch which does work.
 

So on the picture of Table 68 for the headlight switch, ON means the Brown Blue and Red should be connecting. There is a different position called CL where only Brown and Red are connected. I think CL means the headlight is not on, and could be the state that it is in and why I have no headlight working.
So I have to search for where the previous owner connected the 3 together, since my bike has no right handlebar switch, and find the 3 wires and make sure the Blue isn't disconnected or broken somewhere along the path

 

I just removed the ignition switch-on the female side of the connector, on the harness which goes toward the back of the bike, I get 12V from the white wires only-maybe that's normal so I'll continue investigating.  Even after I test the ignition switch I'll borrow a friend's ignition switch and swap to see what happens-

Also, here's the wiring diagram

 

So the ignition switch seems to be checking out ok.  The high/low beam wires and blue wire are not ripped, continuity meter beeps indicating the wires are intact.  So now I think I have to chase the problem on the female connections to the harness where it meets the ignition and left hand switch.  White has 12V going to ignition switch, and I'l have to see if I'm getting 12V on one of the pins on the female 6 point connector to the left switch.  Switching between High/Low beam does nothing, but blinkers work fine.
I did scrape the contacts where it slides between high and low.

 

ok
get your meter

DC V
key on/ignition on
Black probe on neg battery post (post is the metal part of the battery)
Red probe on each of the 3 terminals at your headlight connector.
The headlight must be connected. Just back probe the connector.
note voltages

switch to high beam
note voltages

If the headlight connector is receiving +12v, then one of those wires will be 12v.
One other wire will be 0V.
Yellow/black wire will be 0V.

When you switch to high beam.
The yellow/black should be 0V
The 12v will have swapped with the other 0V wire.

If your yellow/black wire is 12v, then your ground wire is bad.

Turn off bike--do these tests within 5 min otherwise coils will overheat
 

Yeah I'll go through that again, I was getting nothing on the low and high beams at the socket, and also when I disconnected the socket and tried reading direct from the bullet connectors.  Pretty sure I did a continuity test for the black/yellow ground but I'll re-test everything.  Intermittent problems are hard to find.
In the worse case I might try to get power from that double female brown accessory wire that lays around inside the headlight housing
Thanks

With the voltage drop tests I'm having you do the circuit must be complete(nothing can be disconnected) as it won't show corrosion or high resistance.
Continuity tests don't work that well as you can show continuity with only 1 strand of wire.
 

Just started raining and not enough space in the garage to work with car and other bike- for now I'll put the battery to charge since it's been 2 days of testing so I'm sure it went down-
I'll reconnect ignition and left switch and see what I get
Thnx

There's no 12V reaching the headlight.  Somewhere before it feeds the left handlebar switch it failed.  So I'll have to track back into the harness and if needed get a new wire to feed it-
Thnx
JB