This DC brush motor coolant pump is the main ESS Pack cooling device older 1.5 Roadsters.  The later 2.0 and 2.5 Roadsters have two magnetic drive coolant pumps doing the job.

These traditional pumps use a 12 volt direct drive motor with brushes and bearings which wear over time.

We recommend proactive replacement of  this pump every 5 years considering this pump works almost constantly keeping Lithium Ion cells cool in the ESS Battery Pack.  In addition, failed or weak pumps have been attributed to damaging vital electronics in the ESS Battery Pack, like the Auxiliary Power Source (APS) controller which also relies on coolant from this pump.

These pumps usually indicate pending failure by making more noise and becoming more audible.