ESS Battery Pack Coolant Tip
We have had two Roadsters where coolant reservoirs were nearly empty. Both were exhibiting noisy pumps. In one case, the low coolant level, and subsequent ESS pack overheating, caused an APS (DC-DC Converter inside the ESS pack) to fail.
The solution from Tesla was a $30K ESS pack replacement. We pulled the battery pack and repaired the APS to component level. Pay attention to your coolant levels.