External AC Contactor Malfunction

What does F72 mean?

This Manual Fault occurs when the External AC Contactor or a latching relay within the Battery Control System (BCS) is not in its expected commanded state. This signifies a failure in the external AC power path control, impacting power flow.

• Welded contacts in the external AC contactor preventing it from opening when commanded (e.g., detected by auxiliary contact state feedback).
• Failure of the coil (open circuit or short circuit) in the external AC contactor, preventing proper actuation.
• Auxiliary contact feedback circuit failure (e.g., broken wire, stuck contact, loose terminal) causing the BCS to misinterpret the contactor's actual state.
• Internal latching relay mechanism within the Battery Control System (BCS) stuck or unable to switch states.
• Improper wiring or loose terminal connections for the contactor control or feedback signals (e.g., BCS output to A1-A2, or feedback from 13NO-14NO).

Click steps to track your progress.

1. 1

   1. Visually inspect the external AC contactor for physical damage, discoloration from overheating, or signs of welded main contacts.

2. 2

   2. Using a multimeter, measure the voltage across the contactor's coil terminals (e.g., A1-A2) when commanded to change state by the BCS.

3. 3

   3. Verify continuity of the contactor's auxiliary feedback contacts (e.g., 13NO-14NO) in both open and closed states, comparing to the BCS expected state.

4. 4

   4. Inspect all control wiring from the BCS to the external AC contactor for proper termination, continuity, and insulation integrity.

5. 5

   5. Power cycle the Battery Control System (BCS) and observe if the contactor attempts to actuate and its state changes.