GUAC Commanding System to Shutdown

Symptoms

The Grid Utility Ancillary Controller (GUAC) is commanding the site to shutdown when not expected.
Figure 1. Site Shutdown Alert

Steps to Troubleshoot

  1. Identify GUAC LED status. On the GUAC, there are two LEDs. The red LED indicates the device is receiving 12V power. The green LED indicates it is not commanding a site shutdown.
  2. If the red LED is off.
    1. Confirm the 12V is correctly wired, the terminals are tight, and a multimeter reads 12V across the 12V and GND pins.
    2. Fix any wiring issues or escalate to Tesla Support.
  3. If the green LED is off.
    1. Measure the resistance between the DRM IN pins.
    2. Remove the green DRM connector and measure resistance across the connector terminals.
    3. If the resistance is not 15 kOhms, confirm the DRED is wired correctly.
  4. If the green LED is on.
    1. Confirm the GUAC has been wired correctly to the TACO's RSD port.
    2. Confirm the screws have been tightened.
  5. If the issue persists, contact Tesla Support stating GUAC shutdown issue with the status of the GUAC LEDs and resistance value of the DRED.