A pre-session downpour delayed the start of practice, and when it did run for 30 minutes, Ericsson lapped the 2.1-mile temporary street course in 1m31.7999s.
Ganassi’s series dominator Alex Palou was one of the first cars on track, setting the bar at 1m35.0152s, and was also the first to find the run-off at Turn 11, requiring a spin-turn to get back on track.
He wouldn’t be the last, with Friday’s pacesetter Will Power and his Team Penske team-mate Josef Newgarden also doing likewise.
Marcus Ericsson took top spot with 1m33.9812s and worked down to 1m31.7999s.
“It was good to get out when it’s raining as it’s not long before qualifying starts,” he said. “We still have some strange things happening with the brakes [which hampered him on Friday too].”
Rinus VeeKay (Ed Carpenter Racing) got to within 0.8911s of Ericsson for second place, ahead of Power, the third Penske of Scott McLaughlin, Marcus Armstrong (Ganassi) and his team-mate Scott Dixon.
Ryan Hunter-Reay (ECR) chose Turn 4 for his voyage into the escape road after a big slide after coming off the Korean War Veterans Bridge. He finished the session in seventh, ahead of Newgarden, Palou and Agustin Canapino (Juncos Hollinger Racing).
The red flag waved with two minutes remaining, when series debutant Linus Lundqvist stalled his Meyer Shank Racing car at Turn 11. He was 21st quickest.
Alexander Rossi (Arrow McLaren) and Romain Grosjean (Andretti Autosport) were the only cars that didn’t run.
IndyCar Nashville – FP2 results