Sounds like maybe your ignition switch has given up and exploded internally.

I thought the ignition switch was at fault as well. So I opened it up and rebuilt. It looked good on the inside. I could use an accurate wiring diagram. Should I suspect the voltage regulator? The instrument lights are powered from there right?

Further investigation found the diode board held by one bolt. And after research about their reliability, I have ordered a new board and voltage regulator from Thunderchild. It may not solve the problem but seemed like a good investment in the long run. At least I will be working with viable parts.

► If I have the "story" correct, originally the diode board was mounted by rubber, vibration-type mounts which turned loose after years of service. The repair/ upgrade is to replace those with solid mounts, which will never break and also improves the electrical connectivity of the board.

► To clarify.... the indicator panel is not directly "powered" by the diode board. Power to the alternator field winding is also shared with the "Gen" lamp on the indicator panel. So that if the "Gen" light does not come ON with the key, then there is a good chance that either 1) the field winding is not being energized (thus the alternator will have zero output), or 2) the bulb is simply burned out.

Hope this helps.

I have owned the bike for 6 weeks. So kind of new with this bike.
Yes the diode is/was rubber mounted. 3 of 4 fasteners have failed.
After a hard ride this weekend (tried to achieve 100mph) the head light failed. I found a middle green wire to the ignition switch was unconnected. After connecting, the lights work but the instrument lights could only be turned off with the kill switch. Neutral, generator, and oil...Bike starts and runs well. Just have to use the kill switch as ignition. Not a secure option.
Hey, Thanks for the help

► I highly suggest that you disconnect the Negative lead from the battery post for a complete overnight shutdown. The kill switch may leave some circuits powered, which would run down the battery.

► There are numbers on the back of the ignition switch next to the terminals. Make sure the wire colors agree with the terminal numbers. On my 1979 the BLU and GRN wires looked identical in color until a very bright LED flashlight was used. Using the normal overhead shop light, I had used the incorrect terminals.

► You will find that BMW riders are a hardy bunch, and thus all these bikes have been ridden in all sorts of inclement weather. Consequently, water has been thrown onto all the electrical connectors at some time during it's long life. Typically, this water has introduced some amount of electrical terminal corrosion. This electrical corrosion will not be part of your American, Japanese, or English bike experience, since those riders generally pull over and wait for the weather to clear !!

The first step in curing this is to order a very small tube of "No-Ox-Id electrical compound" off Amazon or Ebay. Then with each and every electrical connector you unplug, wipe the male end with a small amount of No-Ox before re-inserting the connector. This also goes for: the 2 fuses inside the headlamp shell, all relays, the back of the ignition switch, battery terminals, main wiring harness ground (BRN) on the LH ignition coil mounting bolt, AND where the sub-harness plugs to the rear of the instrument cluster.

As you add this corrosion inhibiting "grease" to the numerous terminals all over the bike, you will find that individual items and systems all over the bike begin to work better. Lights become brighter. Horn(s) become louder. Starting becomes easier. Typically it's not one single bad connection; it's the sum of all the tiny losses mimicking a single large issue.

That intense scrutiny will also help locate frayed and broken wires that need your attention.

Hope this helps.

Problem fixed.
I think your advice about cleaning up the wires did it, but I also have a new diode board and regulator.
When I had light issues I plugged in a loose wire coming from terminal block #15 to the ignition switch. That started my problems with the "lights stay on". The terminal beside the red #30 on the ignition switch is always hot. It should not be plugged into.
I have no idea where this green wire from block #15 goes to. I left it tapped and floating.
You guys are so patient and helpful towards new owners. We appreciate it.
Wish I could have made it to Salt Lake City.
George

Hey, that's great news ! Congrats.

• You're correct, there is an empty male spade connector on the rear of the ignition switch. That's a great place to plug in your wiring for a phone or GPS charger, as long as you add an in-line 2A fuse. You need the added fuse because the RED wire is unprotected. Should your phone charger short out, it will burn up the main harness. Don't ask me how I know this.

• Continue with the No-Ox treatment throughout your ownership of the bike. It will continue to pay off. There are also several multi-pin connectors that join the harness parts together, and relays are scattered all over the bike. Don't forget to go inside the tail lamp housing. There are lots of connectors in there too.

• So where did you get your diode board mounts ? I need to take care of that issue on my '79 myself !

All the best.

I bought the board, four solid mounts, and a regulator from Thunderchild. I was burned by Canadian customs as it crossed. Two taxes and a handling fee. Next time label it sample or gift.
The wiring harness under the tank, over the coil, left side sure gets squished. Looks like a place for the tank to rub the wires bare. The tank will not fit if the wires are routed beside the ground bolts.
Speaking of electrical fires.

► Right in that same location, on the coil mounting bolts, is a bundle of BRN wires being secured with one of the LH coil mounting bolts. That bolt is your electrical connection to the frame, so a shot of No-Ox is needed there.

► Make a mental note... That other empty coil mounting bolt is a very good place to secure ground wires for running lights and other high current accessories. The best place to ground low current accessories, like cell phone chargers and GPS, are the empty spade lugs on the BRN section of the circuit board inside the headlamp shell. Those are at the very bottom of the multi-color circuit board.

Hope this helps.