Display shows E03 and charging does not start; unit may click once and then drop out.

Safety first: This fault involves high-voltage switching components. Turn off the breaker, verify absence of voltage, and only open the enclosure if you are qualified.

• Listen for contactor operation: When plugging in the vehicle (with power on), you should normally hear a distinct click from the internal contactor. If E03 appears and no click is heard, the coil or driver may be faulty. If a loud buzz or repeated clicking occurs, the contactor may be failing.
• Visual inspection: With power off and cover removed, inspect the main contactor inside the Sun Country Highway charger for signs of overheating: discoloration, melted plastic, or burnt smell. Check that all lug screws are tight (use a torque screwdriver to manufacturer spec if available).
• Manual contactor test (advanced): A technician can test coil resistance with a multimeter and verify that the contacts are not welded closed by checking continuity with the coil de‑energized. If continuity remains when it should be open, the contactor is welded and must be replaced.
• Replace faulty contactor: If the contactor is confirmed defective, replace it with the exact Sun Country Highway-specified contactor model and rating. Ensure all wiring is reconnected exactly as before and torque lugs properly.