The electrical system of the Aermacchi Harley-Davidson M-125 Rapido from 1971, drawn circuit by circuit. Each wire is labelled with its colour.
Always check a wire with a multimeter before you connect it, and disconnect the battery first.
Circuit 1Power from the batteryThe positive goes with the blue wire to the rectifier and through the fuse with the green wire to terminal 3 of the ignition switch. The negative goes to earth.
Circuit 2ChargingThe red wire from the generator goes to the rectifier. It charges the battery with the blue wire. The black wire from the generator also arrives there.
Circuit 3IgnitionThe black wire goes through terminals 6 and 5 of the ignition switch to the coil. The coil gives the spark to the plug.
Circuit 4LightingThe red wire feeds the handlebar switch. It selects high or low beam. The warning lamp gets power through the headlamp.
Circuit 5Tail light and clocksThe brown wire from the handlebar switch feeds the speedometer lamp and terminal 1 of the ignition switch. Terminal 2 feeds the tail light with the yellow wire.
Circuit 6Stop lightTerminal 4 of the ignition switch feeds both stop light switches with the green-black wire.
Circuit 7HornThe handlebar switch feeds the horn with the red wire. The grey wire goes back to the button, which makes the earth.
Read this firstWatch out forUncertain colours and terminals
- Switch table in the book: park 2-3, ignition 1-2, 3-4 and 5-6.
- The inside of the handlebar switch is not shown in this diagram. Check with a meter which terminals are connected in each position.
- The book does not say which wire is high and which is low beam. Where this page does say so, it was worked out from the warning lamp. Check it at the headlamp.
- The negative battery wire has no colour code in the book. That is why it says "colour?".
- This diagram is hard to follow in the photo. Where wires cross, the connection was worked out from colour and function. Check those connections with a meter.
- The black wire from the generator and the black wire to terminal 6 meet on one rectifier terminal.
Our own drawings per circuit. The connections are based on the workshop manual for this model. Not an official publication of the manufacturer.