Bosch
Unstable Contactor Drive / Pilot Negotiation Failure
Bosch EV charger clicks repeatedly (relay chatter) when a vehicle is plugged in, but charging does not start.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Weak contactor coil, Low control voltage from power supply, Faulty pilot negotiation on main PCB, Marginal vehicle communication
How to Fix / Troubleshooting
Safety first: Repeated clicking indicates rapid switching of high-voltage components. Turn OFF the breaker if the behavior continues.
- Try another vehicle: Determine if the issue is specific to one EV. If multiple vehicles cause the same chatter, the charger is likely at fault.
- Power reset: Turn OFF the breaker for 5 minutes, then ON. Test again.
- Listen for fan and LEDs: Confirm that the internal fan and status LEDs behave normally during startup. Abnormal behavior suggests a low-voltage power supply issue.
- Professional repair: A technician should test the contactor coil voltage and pilot circuit. If unstable, the main control board or contactor must be replaced.
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Repair Difficulty
Hard
4/5
Required Part
Main Power Contactor / Main Control Board
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