Is the Relay Noise Indicating a Malfunction?
4 Answers
Relay noise occurs when the relay coil has a stable power supply voltage before the vehicle starts and the lights are turned on, ensuring reliable engagement without abnormal sounds. After starting, if the power supply circuit for the relay coil experiences unstable voltage or insufficient power from the source, it can cause unstable relay engagement, resulting in abnormal noise. Battery Discharge: This can be caused by a discharged battery. Use a multimeter to measure the voltage and check if the battery voltage is below 11 volts. Poor Contact: Possible causes include loose motor screws, poor contact at the relay's main terminals, loose or aged screws on the battery leading to increased resistance, or excessively worn motor carbon brushes.
Last time I rode the Sichuan-Tibet line, I encountered a relay making a clicking noise, and as a result, the headlights flickered on and off at high altitude. A relay making abnormal noises is 90% likely to be broken, especially if it sounds like a woodpecker—tick-tick-tick. Aging electromagnetic coils can cause unstable engagement, or if the contacts are burnt, unstable current can lead to the noise. If you smell plastic on a rainy day, turn off the power immediately! Once, my friend forced the bike to run, and the relay ended up smoking and frying the ECU, costing over 2,000 RMB in repairs. My advice is to first record a video of the noise frequency and take it to a repair shop for diagnosis—never open the relay cover yourself.
A buzzing or clicking sound from a motorcycle relay is usually abnormal. I've repaired too many bikes that ended up stranded due to ignoring strange noises: poor contact at the terminals can cause headlight flickering, a shorted coil can drain the battery overnight, and in severe cases, it may even blow a fuse. Last year, a Ducati had its entire wiring melted due to a stuck relay causing the turn signals to stay on constantly. When you hear unusual noises, first use a screwdriver to pinpoint the exact location. If the sound comes from the black box under the fuel tank, it's most likely an issue with the main relay. Pay extra attention during rainy days, as oxidized metal contacts will make the noise more frequent.
Relay abnormal noises can be divided into three situations: A slight buzzing may indicate voltage instability, but if accompanied by light flickering, be alert; Regular clicking sounds mostly indicate contact erosion; The most dangerous is crackling with a burnt smell, indicating internal short circuit. I've personally witnessed an old CB400 relay sparking and igniting the seat cushion. For emergency situations, you can temporarily remove the relay plug and directly connect the corresponding circuit with copper wire to get home, but you must mark the wire sequence. Never use tap water to cool down the relay - last year a fellow rider did this and caused a complete vehicle short circuit.
