R100GS electrickery puzzle?

[Posh Pete]

So .... the wiring for the heated grips is now back in place. They might even be working! I've made no other changes other than removing the cowl around the headlight and accessing the ignition switch. (I thought I might have to use a live feed from there when I was considering brand new grips.)

The ignition circuit is working fine and the engine spins over strongly with a fully charged battery. However ... the lighting circuit appears to be totally dead. No sidelight. No headlight. No horn. No brake light. No tail light.

When I first tried things, I'm pretty sure the parking light illuminated briefly. Nothing now. However, the telltale lights in the panel now light up when the key is in the parking light position and I don't recall this being the case previously?

The fuses are all fine. Checked twice now - visually and with the multimeter.
There's no obvious breaks in the wiring and the spade connections to the ignition switch are all sound.
All the connections under the tank appear to be as they were before the bike came off the road.
I've removed the two feeds for the heated grips from the main harness and the problem is still there.
Flipping the kill switch makes no difference.

Any suggestions please for a flummoxed airhead rider?

 

[Stirlingmoz]

Does this picture help ?

Just in case you have accidentally displaced or loosened a wire from the back of the ignition switch.

It should give you a start point with your multimeter.

 

[Posh Pete]

Thank you. I think it's an earth issue via the clutch / gearbox switch on the left bar. When I pull it in, the lights, horn etc kick in albeit rather weakly given the state of the battery!

So is it simply a matter of replacing the switch on the clutch housing?

 

[Stirlingmoz]

I don’t think this will be the root of your lighting problem.

It’s just an interlock system to prevent you accidentally starting the bike with a gear engaged.

Having the bike in neutral should loop it out.

Are the three plastic plugs under the tank that connect the handlebar switches to the loom all fully engaged ?

Is the round plug that fits in the back of the warning lights fully home and correctly oriented ?

Can’t help feeling if it was working fine before something has been disturbed.

I know you checked the fuses (for continuity ?) but is the lighting circuit actually getting 12v when switched on ?

 

[kirby morgan]

Pete.
Worth checking the 2 black relays next to the starter relay.
The one marked 512 on the picture. Under the tank.
I had similar and turned out the spade connectors underneath the relay needed cleaning.
May not be, but worth a look.

 

[Mad Hatter]

Or could be the starter relay going duff, or the load shedding relay?

 

[Posh Pete]

Pete.
Worth checking the 2 black relays next to the starter relay.
The one marked 512 on the picture. Under the tank.
I had similar and turned out the spade connectors underneath the relay needed cleaning.
May not be, but worth a look.

Thanks. Will do.

 

[Posh Pete]

Thanks. Will do. :

 

[Posh Pete]

Having the bike in neutral should loop it out.

The bike is in neutral. Activating the clutch interlock switch also activated the horn and lights circuit.

 

[wilbjr21]

Here's what to do Peter .............

Take your multimeter, wire cutters, strippers, crimps and pieces of wire and post them off to a charity shop.

Next take your wiring diagrams and burn them in the hearth to give you some warmth.

Say three Hail Mary's and ask forgiveness from your bike.

Finally ask as a friendly Geordie to come and sort your shite out.

 

[Posh Pete]

That's a very tempting offer Bob. It may come to that bonnie lad. Ye nivver kna!

 

[Fifth Horseman]

With the contacts in the clutch and neutral switches closed it seems there is an unintentional earth path for the lights via the starter relay. If significant current passes through this path it risks damage a component in the relay.
Check all the earth connections to the frame paying attention to the ones at the front of the bike.

 

[Greg Masters]

Dodgy switch?

Check the input and outputs at the light switch...

 

[Posh Pete]

With the contacts in the clutch and neutral switches closed it seems there is an unintentional earth path for the lights via the starter relay. If significant current passes through this path it risks damage a component in the relay.
Check all the earth connections to the frame paying attention to the ones at the front of the bike.

Thanks. That was the broad outline of my thinking too but lacking details re the starter relay.

That's my job for tomorrow sorted then!

 

[Posh Pete]

And breathe ...

All fixed now. As suggested above the earth was the issue. I had forgotten that there's a single earth point with multiple leads on the lower bolt of the electronic ignition heat sink. A bit of scraping and wet and dry and some decent torque with an Allen key and job done!

Ta for the suggestions!

Put the stotty cake away Bob!

 

[Mad Hatter]

Good result!