Charger shows E4 and does not energize the vehicle; fan may run briefly then stop.

Safety first: Turn OFF the breaker before touching wiring. Only qualified persons should measure live voltage.

• Check circuit rating: Confirm the Schumacher EV charger is on a dedicated circuit of the correct amperage (e.g., 40 A, 50 A, or 60 A depending on model). Shared circuits can cause voltage sag.
• Measure voltage under load: Have an electrician measure voltage at the charger input while attempting to start a charge. If voltage drops significantly below the nameplate minimum, the wire gauge may be too small or the run too long.
• Inspect terminations: With power OFF, check all lugs at the charger and breaker for tightness and signs of overheating. Retorque as needed.
• Listen for contactor: When starting a charge, you should hear a solid click from the internal contactor. If it chatters or drops out, the contactor or its coil supply may be faulty and require replacement.
• If supply is stable but E4 remains: The undervoltage detection circuit on the control board may be defective. Contact Schumacher support for control board or contactor assembly replacement.