Instrument Cluster Idiot Lights

I am on to the next phase of bringing a neglected 1983 BMW R100RS back to life. Some of you may have seen and posted on my brake and electrical question last week. Thanks for your responses. I have ordered the Master Cylinder Rebuild Kits along with other parts to keep this project moving.
I am digging deeper into the electrical issue now, trying to figure out why none of the idiot lights on the Instrument Cluster illuminate.
The lights for each gauge work, but nothing else.
I removed the Instrument Cluster and tested each of the bulbs in and out of the cluster, and all bulbs work as expected.
I have unplugged and sprayed all electrical connections with WD40 and cleaned them with a Q tip.
As expected, there was a fair amount of corrosion in each connection.
After doing this, I am getting the Oil light and the Generator light to illuminate. The Turn Signal, Neutral Light and High Beam lights are still resisting my efforts. I am waiting for delivery of another BMW Service Manual as my manual goes up to 1982, and does not have the proper wiring diagrams.
When that gets here, I can trace the wiring to see where this problem lies.
The headlight works, as does the High beam. The Turn Signals work, as does the Brake and Tail Light.

My question to the group:
Is there a Diode on the Circuit Board that could affect this? If so, where is it located? As we are al aware, just because it shows up in the wiring diagram does not mean it is in proximity of the other components. Any thoughts on what components I should look at first to resolve this?
Thanks

I'm the worst to give advice on electronics, but I don't think I've heard of a diode like this that affects the signals in the speedo shell. I have the BMW electrical CD and looked in my 1978 manual and the direct wiring for this shows only a transistor (in my manual)...not sure how that would work in the circuit. What you're probably dealing with is one of two things. The trace on the thin foil is probably cracked somewhere. The second could be the pins that come into the back of the unit...sometimes they have been known to break inside the molded plug. Not sure if you've confirmed that you have voltages coming from the molded plug.

In the end, these parts are NLA. A couple of people have developed a direct replacement that uses LEDs. If you can't get the original setup to work, might be worth considering:

https://katdash.com/

See Matt Parkhouse' column in the November ON where he talks about the replacement board with LEDs.

When I bought my Katdash they recommended the use of DEOXIT to clean the connections. Given the fairly fragile nature of the connections, I would also recommend it to remove corrosion. It's fixed a couple of problems I have had with electrical connections.

KatDash

A good thing to have when you are working on electrical systems is the very nice, large color and pin coded schematics EME sells. They beat anything I have seen in the BMW repair manual as well as Clymer. By pin coded, not only does it show the color of the wire, but if there is a numbered connection like on the headlight relay, the PIN number is marked.

My feeling and it is only personal is to dump the bulb system in the instrument cluster for the aftermarket Katdash system. Over the years I have owned my two bikes, I changed a lot of bulbs in the original system and each time I had to change a bulb, I noticed more and more deterioration of the bulb socket material. Soon it got to be I was taking the cluster apart just to mess with the connections to the bulbs. Each time the bulbs have to be changed all the little screws holding the housing together have to be taken apart, well, one by one they broke. Finally, the Katdash hit the market and I dumped my bulbs, bought a new housing from Siebenrock, and at the rate I am going I hope never in the rest of my life to have to take the cluster apart again. So far the best money spent.

I can concur with the advice given by others, the bulb sockets are not all that durable. the pins on the plug are sometime prone to corrosion. IF the connector from the main wire harness is shot, there is an aftermarket plug which can be used, without having to replace the main wire harness. https://www.siebenrock.com/en/electric/instruments/3558/repair-kit-harness?c=632 Boxer 2 Valve may have the same kit or Wunderlich.

For the neutral light and oil pressure light, don't forget to check their plugs and the connections into the main wire harness. I found in my current overhaul my neutral light sub harness was shot from corrosion. The light was still working but the harness was in bad shape so I along with most of my wiring harnesses replaced it with parts from EME.

I bet with the schematic and fiddling you will get things right. Cheers, St.

Third Katdash

WD40 and a Q-tip ain't gonna get the job done. Some lights came on showing you are on the right track but you need to use 400 grit sandpaper to clean the corrosion. Detox is great to finish the job in the female pins on the plug. The Katdash LED conversion is well worth it and instantly solves the poor connections. If the alternator bulb burns out the bike will not run!

Generator bulb

The bike will run with the generator bulb burned out, at least until the battery goes dead.

The bulb is needed in the circuit in order for the charging system to work, the bike can and will run without the charging system working until the battery gets drained to the point where spark cannot be produced.

It is always a good idea when turning on the key and before starting the bike to look to see if the bulb is lit up if not, there is a problem. St.

Instrument CLuser Idiot Lights

There is a Diode in the system in the form of a relay.
When I turn on the ignition, I hear a click from the left side of the headlight housing as I am sitting on the bike.
When I looked closer at the really, I noticed the red lead is frayed, and has broken down in several places.
Tracing it as well as I can, it appears that this lead goes to the battery and is fused.
What I do not know is if this lead splits off anywhere else.
A quick test from the Ohm Meter shows a problem, so I need to dig further.
I will test the relay as well as looking at an older wiring diagram in the hopes that I can sort out if and where this red lead may go other than to this relay. If this is a direct connection, I will put a jumper across the leads and see where that takes me.
I am still waiting on the delivery of my manual with a proper wiring diagram so I can trace these leads.
Does anyone have a wiring diagram for a 1983 R100RS that they can scan and send to me for the near term?
All diagrams I have fond online are not adequate as they do not show the connections into the headlight nor the gauges.
I have contacted EME and requested information on their wiring diagram, but that will also take some time before I can get it ordered and have it delivered.
Thanks

Eme

If you go online to Euro Motoelectrics or EME, they have the very good plastic matted wiring diagrams. As I wrote earlier, these are not only color but have pin locations marked with the connector numbers as well. Far better than the ones in my BMW manual or Chiltons.

Also, check out this website of Brook's, he just restored an 83 bike, while he converted an RS to an RT, the wiring is the same just the wires on the handlebar controls had to be lengthened. In is pictures he has a couple of spread sheets giving the source of the wires, and their locations in the headlight shell. His pictures and videos are fantastic.

I have relied on his documentation while overhauling my 83 R80RT. Even with the nice schematic it is nice to have good pictures and video of what is what and how it all goes together. We owe Brook a beer for taking the time to do what he did.

There are only two fuses in the original 83 wiring. any red wire with a fuse in it is not stock. The red wire you are talking about I believe is part of the main wiring harness. Good luck, St.