How to Fix / Troubleshooting

Safety first: De-energize the EVSE before testing the contactor coil.

Step 1 – Listen for click: Command charging on and off while listening for the contactor. No click suggests that the coil is not energizing.
Step 2 – Coil resistance: With the power OFF, disconnect the coil leads and measure resistance across the coil. An open circuit indicates a failed coil; therefore, replace the contactor.
Step 3 – Check coil voltage: With the power ON and a charge command active, measure the voltage at the coil terminals. If no voltage is present, the driver on the main board may be faulty.
Step 4 – Inspect wiring: Ensure coil wires are firmly connected at both the contactor and the main board, and that any auxiliary feedback contacts are wired correctly according to the OpenEVSE schematic.
Step 5 – Replace parts: Replace the contactor if the coil is open. If the coil is good but not driven, replace or repair the main control board.

The display shows 'RELAY ERROR'; the EVSE cannot energize the output even though the contactor is not welded.

Possible Causes