1996 F3. When I turn the key to on, i get no lights on the cluster like usual, and everything is dead. No horn, headlight, nothing. Checking with a multimeter, the ECU under the seat does get power. I'm thinking it could be a problem with the ignition? Anyone ever had this frustrating problem?

 

I'd suggest start looking at the fuses.

 

I'd check your voltage regulator. Mine fried, and it has no power to the horn, or starter and the low beam was blown, try your high beam and see if it lights up. But my first guess would be your voltage regulator/rectifier.

 

Meant to also add. Checked all the fuses. They all passed continuity tests.

 

just check the main fuse under the seat next to the wires, that's all it is probably.

 

I'd say main fuse under seat or rectifier

 

If it is your rectifier the plastic plug that connects to it will have burn marks or melted plastic.

 

Not the main fuse under the seat. That one (30 amp right?) was fine.

Where might I find this rectifier?

By the way, thanks for all the help. Much appreciated!

 

It's on the right side of bike middle of seat on the side of frame. Right side if your sitting on the bike. Take the plug out look for burn marks.

 

Being that you are getting 13.5 volts at your battery most likely your rectifier isn't the culprit because if it was your battery would be dead. If you're certain that all your fuses are good(and it seems like you are) I would lean more towards a loose connection at your battery cables.