Symptoms:
Loss of communication with the Bridge.
Troubleshooting Steps:
Check for LEDs on the Bridge PCBA.
If No LEDs:
Confirm that grid power is supplied to the Bridge.
Attempt a power cycle (see article 99.2 Power Cycle Lunar Bridge).
Check connectors on the Bridge PCBA.
If LEDs are Present:
Verify CAN cable wiring at the terminals of both the inverter and the Bridge are properly landed using a gentle tug test.
Confirm that CAN Hi / CAN Low wires are landed on the correct terminals.
If necessary, use a multi-meter to verify voltages: 13V to GND → 13V | CAN HI to GND → 2V | CAN LOW to GND → 2V.
Push a FW update.
If communications are still not established, disconnect the trunk harness to reduce the number of devices on the CAN bus.
Potential Causes:
A firmware problem on the Bridge.
The Bridge PCBA may be physically or electrically damaged.
The comms wire between the Bridge and the Inverter may be unplugged at one end or damaged.
Remote Diagnosis:
Look for recent firmware updates. A communication drop after a firmware update likely indicates a firmware mismatch or the device being stuck in bootloader. Attempt another firmware update and escalate to the firmware team if this does not resolve the issue.
If no recent firmware updates, check Grafana for the number of CAN bus comms errors. High error counts indicate poor wiring, necessitating a service visit.