Charger display shows E04; unit powers up but will not start charging when connected to the vehicle.

Safety first: Turn OFF the breaker and verify the charger is de‑energized before opening any covers. Internal components carry lethal voltage.

User-level checks:

• Power cycle: Turn the breaker OFF for 5 minutes, then ON. Sometimes the control board will clear a transient contactor feedback error.
• Listen for contactor click: With the cover closed and power ON, plug in the vehicle and listen for a distinct click from inside the charger. No click or a loud buzzing suggests a contactor issue.
• Check for overheating signs: Feel the outside of the enclosure (it may be warm but should not be hot). Look for discoloration or a burnt smell around the unit.

When to call a technician: E04 typically indicates an internal power relay/contactor problem. Do not attempt to open or replace the contactor yourself unless you are a qualified electrician/technician. Contact Cadillac EVSE support or a licensed EVSE service provider to test and replace the main contactor or control board as needed.