1983 BMW R100RS How To Use Wiring Diagram To Learn About Neutral Switch & Starter

[@MasonicInc]

7 years old and Brook's is still helpful...

[@Steve.Miller]

Great video, thanks. Question; does the neutral light filament figure in to the circuit? Does a burned out bulb cause the circuit to malfunction?

[@rickmacpherson1413]

Very nicely explained for some of us that view wiring as Voodoo Science! thank you Brook.

[@BrooksAirheadGarage]

Rick, Thanks. I wanted to see if this approach helped show how to extract only what you need to focus on from the complete diagram.

[@timbenbow4903]

Thank so much. I replaced my wiring harness and had this problem until I engaged the clutch. How can I get the neutral switch connected. Tim

[@BrooksAirheadGarage]

Neutral switch is on the bottom of the transmission toward the rear. Remove rear engine mounting stud and then remove the tube between the ears of the transmission. You can access the wires to the switch and connect them.

[@eduki]

Very helpful! I have my panel lights defective since (i suppose one of the previous owners) a "mechanic" put his hands on it, and when neutral light mights light on, it lights the GEN RED light, and viceversa, when GEN light must show, it shows the GREEN neutral bulb...

[@BrooksAirheadGarage]

Eduki, if the bike is a /6 or later, that behavior suggests the pins in the large black rubber connector block that plugs into the back of the instruments got switched during a repair.

[@eduki]

Motorcycles and Other Musings thanks a lot! I'll check it to solve it, I'm enjoying your videos, very informative and interesting!

[@eduki]

Thanks again! Do you know where is it located?

[@BrooksAirheadGarage]

eduki, I have a diagram the applies to the /6 series here: flic.kr/p/QCcQR8 The circuit board changed over the years with the electronic tachometer instead of mechanical, moving the brake master cylinder to the handlebar and relocation the turn signal indicator light from the bottom on the /6 to the top later in the /7 series. I hope this helps.

[@speedstersa]

Thanks for your diagram...

[@BrooksAirheadGarage]

You're welcome Steve.

[@paulgarza8389]

Thank you ! I totally trust the structure of the layout you have provided for the world of Airheads. I'd like to to pose a question to a problem I have going on with my neutral safety switch on a 78 R100/7 . I will provide a list details with the issues. Will this be okay ?

[@BrooksAirheadGarage]

Sure. I'll help if I can.

[@paulgarza8389]

1) good battery 2) Ignition and kill switches both function properly 3) Newly installed starter relay beneath tank 4) Clutch switch & start switch both function properly 5) New neutral switch under tranny = PROBLEM is.. no illumination to the green cluster neutral light. I have conducted the test on your refresh video and that does not illuminate it. I have bypassed both connectors that fit into the neutral switch blades and still no illumination. I have disassembled the cluster and ran 12V on the bulb itself, the bulb is good. No illumination to the neural light at all - The oil pressure light + alternator + signal blinkage are all functioning as designed. Ideas on the neutral issue ? (popped open the headlight and verified that the correct wiring w/ in 85b is in its place) - thoughts ? ..thanks Pg

[@BrooksAirheadGarage]

1. Larger rubber connection to the back of the instrument cluster has sockets that connect to pins in the instrument cluster to power the neutral light. Socket-pin for neutral not making contact, or dirty/corroded. 2. Broken copper trace on the flexible board inside the instrument cluster. Look at the flap that folds over the edge of the hole the bulb socket plugs into. The copper foil is often cracked/broken here. Could also be cracks anywhere along the path. 3. Wire going to neutral light in the bundle that connects to the larger rubber connector in that plugs into the instrument cluster is corroded/broken inside the harness. 4. See this write-up on my site for more details: brook.reams.me/bmw-motorcyle-rebuilds/1983-bmw-r100rs-rebuild-project-index/62-bmw-1983-r100rs-repair-instrument-circuit-board/ Hope these are helpful.

[@bobvansand6346]

Thx, my rs 100 year 79, doesnt give me any light at all...zero...after a spark to the frame...as a result...where to start? Bob Belgium, this video clears a bit the mist, thank u!

[@BrooksAirheadGarage]

Hi Bob, I made an error in the hand drawn wiring diagram. In my effort to simplify things, I got carried away. On the Starter Relay, I show three wires together on a single terminal. That is wrong. The wire from the starter switch should be drawn as going to a separate terminal (85). The other two wires, from the neutral bulb and the kill switch, are attached to the same terminal (86). Updating this video to correct that diagram has been on my "to do" list for awhile. I hope to make a new version of this video with the corrected wiring diagram in the not too distant future.

[@bobvansand6346]

Brook's Airhead Garage , thanks, i check my hanes and see what my 79 rshas as a wiring diagram, should be similar hé?, thanks for great effort! bob Belgium!😎🇧🇪🍺

[@silentoperator1]

Thank You Sir.

[@paulgarza8389]

Mr. Brooks - advice please - 1978 R100/7 - headlight hi and low beam not working not turning on - NEW left handlebar headlight horn switch + Headlight bulb was tested from a known working bulb from my R90S + Headlight relay was tested from known working relay from my R90S - No prior tampering in the /7 bucket + turn signals / horn / right side starter switch / rear tail light / oil light = all work (just dont know where else to start looking) any ideas, suggestions would be helpful and admired - thank you - Paul

[@BrooksAirheadGarage]

Hi Paul. I would verify that the headlight relay is working. It is located inside the headlight shell. You should hear it "click" when you turn on the ignition as I believe your year/model bike sent power from the ignition switch to the headlight relay when you turn the ignition switch on. If you have a volt meter, you can verify if there is 12 volts on terminal with the YELLOW White wire when the ignition is on. You can verify that the wire from the ignition switch is sending power to the relay by testing terminal 86 which has a GREEN wire attached. It should show 12v when the ignition is on. I hope that helps.

[@paulgarza8389]

@@BrooksAirheadGarage Thank you for your reply (I'm 5 hours late) so.. The relay does not click. It's a known good relay borrowed over from my R90S. I even went to O'Reilly and bought a new one to no avail. The switch has 3 headlight positions. The always on low beam, the up position high beam and the downward spring loaded high beam flash for forewarning the drivers in front of me that im fixing to pass them up. Thats the only function that works ( Only the hi/lo does not) (and the horn, it works too but not the problem) There is no power/voltage bridging across the two fuse terminals. Ugh old bikes - I love them except now. Should I look outside the headlamp bucket or is the problem inside the bucket ? (has to be huh) ? Any info. would be appreciated. Thank you. Pg

[@BrooksAirheadGarage]

@@paulgarza8389 If you don't hear the relay click, it is not working. As I mentioned earlier, you need to use a volt meter to verify if there is voltage on the GREEN wire on terminal (86). The fuses are not part of the headlight problem. The headlight power does not go through them.

[@paulgarza8389]

@@BrooksAirheadGarage yes sir, green wire on the h/l relay is reading 12v and even when unplugged from the relay and meter +probe fed directly into the wire (green) , this too reads 12v - (plugged it back) (and also using the brown ground wire on the headlight tri-plug as ground w/ the meter black ground probe.. 934 pm - Monday

[@paulgarza8389]

@@BrooksAirheadGarage YELLOW &White wire that goes to the H/L relay -- nothing - No 12v reading when ignition is on (green wire does have 12v when ignition is on though

[@Prateekyzf]

Thankyou Sir :)