Reading a Kreidler wiring diagram and finding faults
Published on 7 October 2026 · 2 min read
Electrics are the area many home mechanics avoid. Unnecessarily: a Kreidler's system is simple, and with a multimeter and a diagram you will almost always get there.
How a diagram is built up
A moped diagram has only a few building blocks: a source (the coils on the stator plate), consumers (lamps, horn), switches and the earth. The earth is the frame itself — every circuit returns through it.
Kreidler's wire colours are reasonably consistent, but colours fade and every previous owner had their own ideas. Trust your meter, not the colour.
What you need
A multimeter. Nothing more. Set it to continuity (the position that beeps) for connections and to volts for voltage.
The golden rule: earth first
Nine out of ten electrical faults on an old moped are earth problems. Rust between frame, engine casing, headlamp shell and mudguard breaks the return path.
Measure between the lamp's negative terminal and a bare spot on the engine. No beep means you have found your problem. Clean the mating surfaces back to bare metal and secure them with a serrated washer.
Step by step fault finding
No spark. Measure the ignition coil resistance against the specification; check that the points open and close; check the condenser. A failed condenser gives a weak orange spark instead of a strong blue one.
No lights, but a spark. The lighting coil is a separate winding. Measure whether there is voltage at its output while the engine turns. If yes, work towards the switch and lamp. If no, the coil or the wiring to the stator is faulty.
Tail light only, no headlamp (or the reverse). Almost always the light switch or a connection inside it.
Bulbs blowing. Excess voltage. On a system without a regulator this happens when the load disappears — for example when the tail light has failed, sending the whole output to the headlamp. Always replace both bulbs together.
Everything works but flickers. A poor connection letting go under vibration. Work through every connector.
An old loom
Brittle insulation, green copper strands and unreliable connectors cost you more time in fault finding than a new loom costs to buy. If the loom is in poor shape, replace it in one go rather than one wire at a time.
Work methodically
Always start at the source and work towards the consumer — or the other way round, but pick a direction and do not skip steps. Measuring at random means measuring everything twice.
Parts for this article
- Kabelboom Kreidler serie 1 rmc - €49.00
- Kabelboom model knipperlichten kreidler rs - €118.00
- Kabelboom kreidler rs - €56.00
- Kabelboom mod+ knipperlicht kreidler rs - €126.00
- Kabelboom kokusan electr. ontsteking kreidler, zundapp - €8.00
- BROMFIETS 517 529 530 KREIDLER Ontsteking geforceerde koeling + vliegwiel cpl. ALS MODEL Kokusan 50cc met 6V spanningsregelaar/kabelboom spann. bobine ELEKTRISCHE DELEN Buitendiameter: 90mm - Afstand bevestigingsgaten: 80mm - €137.00