Originally Posted by disston
Before you buy the very expensive ignition switch check the plug to the rear of the instrument pod. This large rubber plug is held in place by a small screw. It is not often a problem but the contacts when they get to the age of our bikes have become dirty for one thing and they have also lost some of their grip. the female part you will see is the rubber plug and the male part is the back of the instrument pod. Clean all of this. Look for any loose pins or holes in the plug that look enlarged. Sometimes they need a little adjusting. It's kinda hard to put contact grease on each pin but if you do just a tiny bit now and again you may avoid making a mess.
Actually all the wires in the bike should have their contacts cleaned and dielectric grease applied as you are working around them.
I'm not sure you have found the problem with the headlight switch. It seems you have jumped to this conclusion a bit. But tell me have you tested the switch to verify that it is the problem? I guess you have to unhook it and test for continuity. That sort of test I think.
Edit; Or do I misunderstand you, is what you are saying is the key does not turn?
MY TROUBLE SHOOTING:
I have my 81 R100 next to the R90 and both headlights are off.
The biggest difference are the fuses on the R90 are mound on one of the '
Checked the battery connection= good and fully charged but can guaranty the life/value of the battery without having it fully tested
Checked the connections to headlight fuses ( not blown and changed out to two new ones)
Checked power to the switch ( 12.65 volts from red lead)
Battery charger on battery while test switch. Light came on for with parking light. Switch will not switch to full open position. Pressed the start button and the whole system died again.
Will test continuity in the morning.
Will change out for a new battery in the morning.