Intermittent lighting problem

Learned gentleman,

I have an intermittent problem with my headlight. Some days it runs fine and some days it doesn't on these occasions I have no headlights with the exception of the high beam when holding my thumb on the passing/flashing button. This is very tiring after a few miles, there is nothing consistent in circumstances so I am puzzled. Also note that here in Oz the ignition is hardwired to the ignition. Suggestions on where to start looking please.

Buck

Jim, Et al,

Sorry for that, it is an ST1300 (2003).

Right now I have no low beams but my high beams work. Looking at the schematic, it must be the switch .

I'd suggest taking out the 2 screws that hold the switch pad together and spraying the headlight dimmer switch with contact cleaner .

or ground issue

Buck said:

I have no headlights with the exception of the high beam when holding my thumb on the passing/flashing button.

Click to expand...

Therein lies the problem, just apply some sticky tape to the Passing button.

No?

Okay, lets look at the symptoms:
The headlamps fail to illuminate, this should be pretty easy to track down.

• If both high, and low beams fail, then it's reasonable to assume that voltage is not getting to the Dip Switch, which receives +12vdc on the Blue/White conductor from the Start Switch.
• If you have a voltage meter, you might start by testing for voltage between the Blue/White conductor, and chassis ground (the Start Switch interrupts the headlamp circuit when starting the engine, and is known to suffer from dirty contacts).
• Continuing along the circuit, we see that the Start Switch headlamp circuit receives +12vdc on the Black/Red conductor from Fuse D (10A, labeled HEADLIGHT).
• Again if you have a voltage meter, you might test for voltage between the Black/Red conductor, and chassis ground.
• Note: Fuse D receives +12vdc on the Red/Black conductor from the Ignition Switch. This circuit is probably fine as we'll see in the next part.

The high beams illuminate with the Pass Switch engaged.

• The Pass Switch receives +12vdc on the White/Green conductor (and passes the voltage back to the Blue conductor (high beam) of the Dip Switch. This is good to know, as it demonstrates that the circuit from the Dip Switch 'out' to the headlamps is working as intended).
• The White/Green conductor receives +12vdc from the Main Stop Relay, which in turn receives +12vdc from the Ignition Switch via the Red/Black conductor (which we discussed above).

All of which leads me to suggest:

1. Check Fuse D.
2. Clean the Start Switch, with some plastic safe contact cleaner (something like Techspray)
3. Clean the Dip Switch, same thing as the Start Switch.

I had the same problem with my ST1100 and it turned out to be the starter button. Take it apart, clean with contact cleaner and use a pencil eraser on the copper contacts. Some dielectric grease on reassembly and you should be good to go.

Thanks to all,

Saturday here so time to go look.

Buck

As I mentioned earlier, my brights worked but not the regular headlights .

I pulled apart the switch pod and sprayed contact cleaner but the lights still didn't work.

I probed the white wire coming out of the switch and after piercing the probe tip into the
white wire, I saw 12v , and now the lights are working correctly .

I guess the switch wasn't working, but my manhandling brought it back to life .

I hope it holds up as i don't see any easy place to disconnect the wires and I don't want to solder new wires inside the switch pod.