Now then, after much banging of head against wall with what seemed like a simple electrical problem, I`m at a loss and I thought I`d ask for your help. It`s a bit of an epic so please stick with me.

I know that there are some oracles of all things electrickery on here, so I humbly ask for your help, here goes.....



If I turn on the ignition and operate the indicators without the engine running, they work perfectly.

If I start the engine, they stop working.

If I turn on the sidelight with the engine running, they will work sometimes, others not.

If I turn on main headlight with the engine running, they will work perfectly.

If I disconnect the headlight with the engine running they stop working but will start working again if I put the plug back on the bulb.



I`ve also tried three different flasher units - exactly the same problem with all of them.
O.k. so I`ve double checked everything. All earths and connector blocks seem good and I went as far as stripping the whole headlight area and took all the insulation off the front of the loom back to the headstock to look for chafed wires. I found one, which was from the engine stop switch on the right hand side so taped that up but everything else looks fine. I also took the ignition switch to pieces and cleaned it out and freshened up the contacts There are a couple of repaired wires in the front part of the loom but the connections are good. I opened up the switches on the left hand bar and had a look, seems to be clean enough. Put it all back together and it`s still exactly the same. The indicators aren`t original by the way, they`re mini aftermarket ones but they are just bulbs and not LED`s.
It`s as if the engine is stealing the power to the indicators when you start it but the headlight is giving them their power back when you turn it on.
Following advice to check earths, I had another look .
I ran some separate earths from the indicators and the problem is still there. I`ve checked that there is no voltage drop in the live feed and that the battery is receiving charge so the reg/rec seems o.k. I then decided to check the continuity on all earths, so I set the multimeter to continuity buzzer and went to every earthing point in turn, all good. Then I attached the probe directly to the battery negative and went round all the earths again, all good. Out of sheer desperation / frustration / curiosity I started poking at every terminal I could find.
Now then, when I disconnected the switchgear on the indicator side and started to poke at the connector block on the loom, most of the terminals were giving continuity. I pulled the connector off the headlamp bulb and stuck the probe in and I am getting continuity not only to the earth but also to the high beam wire directly from the battery negative. Please correct me if I`m wrong, but doesn`t this prove that there is a breach between the lives and earth??


Now I`m normally not too bad with electrics and can usually find a fault even if I can`t fix it I`ve poked the multimeter into every connector that is in the indicator circuit and checked the earthing as best as possible and can`t find any obvious fault. Am I going mad and missing something that`s staring me in the face???
I`m totally stumped.....HEEELLLLLLPP!!!!

Help indeed.
This is weird. Just logged in to type this up.

Our 3TB has just developed the same fault as you described. The only that happened in the moments prior was that the battery terminals had loosened. Tightened up, weird O'weird indicator headlight interaction.
Help us somebody.

Cheers
Min

Here is another wee clue.
At tick over before the battery is charging the indicators will flash occasionally. If I increase the draw on my battery by turning the hot grips on the indicators will work.
So the headlight thing is a red herring.

Still pulling my puzzler so I am.
Min

Since the indicators work OK only when there is a load on the battery e.g. from hotgrips or headlight, both of which will lower the battery voltage somewhat even with the engine running.
I'm wondering if your voltage reg/rec is overcharging and upsetting the flasher unit, combined with smaller indicator bulbs?
What is the battery voltage with and without the hotgrips and headlight on?

Bob

__________________
Remember that Assumption is the mother of all f**k-ups.

If the indicators work ok without the engine running then it would point more to the reg/reg being faulty. How is the battery fluid level? Low? Battery getting hot? If low and/or hot then pointing to rec/reg problem.

As others have suggested it could be reg/rectifier, if you have checked all the earths then it could also be coil on the stator breaking down. If it were me I would replace battery and reg/rectifier but don't buy a cheapo Chinese one, I've been down that route and my experience is not good with the cheap ones.

14.2v no lights
13.2v with lights
All at tick over. No increase with revs.

Reckon that's the culprit alright as looking at the 3 way connector into the headlamp there is a wee bit of melting of the right hand connector looking at it face on.

I'll order one up and report back

Cheers
Min

Mine was melted too, just remove meltet part and connect a spade on the wire and connect. Make sure the rest is tight when you connect.

14.2v no lights
13.2v with lights
All at tick over. No increase with revs.

Not sure if you mean the reg is the culprit, or the melted connector, but the voltages are normal, so reg is OK.

Bob

__________________
Remember that Assumption is the mother of all f**k-ups.

Did you replace the stock indicators with LED indicators???

Stock indicators. But still need headlight on for them to come on.
Reg rec reads out OK.
Headlamp connector replaced as the black connector had melted it.
13.4 v to headlight. Too much ???? Standard 60/55w H4.

Cheers
Min

oh ok... I was just asking because if one replaces the stock indicators without replacing the flasher relay for a led flasher relay they won't draw enough power for the stock flasher relay to actuate..

The ground cable melted the connector???
Only reason I recon could make that happen is a loose connector at the black plug causing excessive heat buildup..
it's something that happens alot in house wall sockets.. if the cables aren't tight enough heat builds up and burns it...

I replaced the new flasher relay ( standard bulbs) with a round tin type from my Guzzi. Although this particular one makes the indicators flash too quickly I don't need the headlight on for them to flash.

Getting close to the answer, another flasher ordered up.

Cheers
Min

After a few purchases this cheap adjustable flasher from ebay has cured the problem.

Motorcycle Turn Signal Indicator 12V 2Pin Speed Adjustable LED Flasher Relay ZR | eBay

Cheers
Min