Boxerworks.com

go to this site:
http://web.eecs.umich.edu/~deroo/bike.d ... hdata.html

This will give you an R75/5 list of vital specs and a schematic. I called it up just before I posted the address and it's a good address. Then I hit send before I told you what it was!

Ok guys. here's the update:

I tested the rear light wires for voltage. The black/silver is 12v, the green/red is not until I depress the foot lever. So good there. I tested voltage and continuity at the rear switch - good as well. But the front brake switch, according to the clymer manual, should read 1 on multimeter as is and when depressed, should have low ohms (I think I explained this right). It is not. So is it safe to assume I need a new front brake switch? From what I can tell in the schmatic that Jean provided, it is either a faulty front brake switch, signal flasher or starter relay, unless I am missing something else.

In the ohms scale you should see a very low reading when the switch is activated. To check with ignition on just short the two pins together, light should light up. If it works when shorted and not when activated with lever you have a bad switch.

Now I would check the connector at the harness. To be sure it's not just a lousey corroded connection.
Follow the wires from the switch to the harness connector and unplug it. Check for corrosion, then short across the harness terminals and see if the light comes on.

jag beat me to it

Probably the front lever switch. When the lever is NOT pulled the switch is open therefore infinite resistance (maybe the "1" reading on your digital meter). When the lever is pulled, it ought to read "0" or nearly that. You should not measure resistannce when VOLTAGE is present...could mess-up your meter.
OH, I forgot the rule - Do not assume.
Do you know for sure the BRAKE-light filament lights? While the tail light is lit, jumper across the connections and SEE if the other filament works. You might have a faulty connection THERE. I hate it when you tear out the front wiring, etc and eventually discover the problem is in the socket. (As if I've NEVER done THAT!)

I doubt the flasher is the problem as the connection there is only a "connection-point" for the BRAKE light. The starter relay does not influence this circuit either. The connection THERE is likewise only a connection, and if the bike starts and runs, it is OK UNLESS a wire is actually broken. SO...to check for THAT do the following:

Check for VOLTAGE at the terminal on the flasher relay (terminal 31) where the GREEN wires are. Should be 12 v. with the main switch ON. (Are the "instrument-indicator lights ON? If so you ought to have 12 v. there, it's the same connection.)
THEN check for 12 volts at the little terminal board where the GREEN/red tracer wire is...ought to be "0" with the lever not pulled and 12 v with the lever actuated. If you have 12 v. on the green wire at the flasher and do not have 12 v. at the GREEN/red tracer wire on the terminal board (bottom of the shell) you have a broken connection or a faulty switch. The switch CAN be repaired...it's just really tiny stuff to solder if you have a broken connection.

PS. I print a working copy of the schematic and use highlighters of the correct main color to show the wires I want to test. It gets confusing when I look at all the black-and-white lines in the headlight shell picture and am trying to do testing at the same time.

hudson wrote:Ok guys. here's the update:

I tested the rear light wires for voltage. The black/silver is 12v, the green/red is not until I depress the foot lever. So good there. I tested voltage and continuity at the rear switch - good as well. But the front brake switch, according to the clymer manual, should read 1 on multimeter as is and when depressed, should have low ohms (I think I explained this right). It is not. So is it safe to assume I need a new front brake switch? From what I can tell in the schmatic that Jean provided, it is either a faulty front brake switch, signal flasher or starter relay, unless I am missing something else.

The front switch an be adjusted further in or out of the perch with the lock ring. If it's too far in it won't come on.

Ok guys -will do the further testing and find the culprit. Thanks!