Headlight not working / LCD not cycling

Fired up the bike today and the headlight did not turn on. I checked the obvious - fuses, lightbulb, and obvious shorts but also noticed the LCD display not cycling. All the warnings are visible with the bike running.

Looking for anything specific to check out before a full diagnostic. Any specific relays? Maybe the relay under the voltage regulator?

 

The head light relay (under the regulator) and the CMS LCD display are initiated by one leg of the AC Generator. So, you either have a non-operating AC Generator or an issue with the wire that connects the AC Generator output (white wire) to the CMS and head light relay.

A good place to start would be to check the charging system. Check the voltage across the battery and look for 14.5V +/- .3 at 2000 rpm and up.

 

If your charging system checks out, you can check the function of the wiring per the instructions below. Note this is also a good way to activate the CMS if doing troubleshooting and not wanting to run the bike. The common point for the white wire is a splice about 5 inches up from the Rect/Reg connector.

 

Thank you for getting back to me and great advice! When I apply the 12V to the male prong, everything works as normal. Does this mean my stator is bad?

 

Not necessarily the stator, but it does mean the charging system is not outputting a voltage or a bad connection at that connector, which is fairly common as they tend to overheat.

So reassemble after cleaning and inspecting the stator connector, and check the charging system as stated above. The FSM has a very thorough diagnostic guide for the charging system. If you find the charging system is not working, or you need help with the FSM guide just let us know.

Or, go ahead and check the resistance of the stator and field coil (rotor) while you are there. The stator wire to wire should be .46 ohms between any of the three white wires (female side). However, because of the low resistance usually reads around .6 to .8 ohms. The rotor should be 4 ohms, but at the connector through the brushes it also usually reads higher, but should be less than 10 to 15 ohms. The closer to 4 the better, so anything much above that would suggest a check of the brushes and cleaning of the rotor should be done.