Display shows HI and pump shuts down or will not start.

Safety first: Turn off power at the breaker before opening any electrical enclosures.

• Confirm pump rating: Check the Hayward pump nameplate for rated voltage (e.g., 230V only). Ensure it is not connected to a higher voltage source.
• Measure line voltage: With a multimeter and power on (only if you are qualified), measure voltage at the pump terminals. If it exceeds the rated voltage by more than about 10%, contact an electrician or your utility.
• Inspect control panel wiring: If the pump is fed from a Hayward automation panel, verify the correct breaker size and wiring configuration per the installation manual. Incorrect transformer taps or miswired legs can cause over-voltage.
• Check for shared neutrals or miswired 120/240V circuits: Ensure the pump is wired as a dedicated 240V load if required, not across a 120V leg and neutral incorrectly.
• Internal fault: If measured voltage is within spec but HI persists, the pump’s internal voltage sensing circuit in the drive may be defective and the drive module may need replacement.