The team announced Tuesday that Ericsson will pilot the No. 7 Honda. The Swedish driver is expanding his racing career into North America and won't join Schmidt Peterson until after the F1 season finale in Abu Dhabi.
Ericcson will remain a reserve driver for Alfa Romeo Sauber F1 Team after his move to IndyCar.
Wickens is paralyzed from the chest down from injuries suffered in an August crash at Pocono Raceway. He drove the No. 6 Honda in SPM's two-car lineup alongside Canadian childhood friend James Hinchcliffe.
Wickens said last week the extent of his injuries are unclear, but that he is hopeful he'll be walking in 24 months.
SPM reiterated Tuesday "the No. 6 Honda remains open for 2018 IndyCar Series and Indianapolis 500 Rookie of the Year Robert Wickens when he wants to and is able to return."
Ericcson won championships in Formula BMW UK, Japanese Formula Three and was twice named Swedish Junior Racer of the Year. He's previously competed in British Formula Three, GP2 Asia, GP2 and currently has 95 starts in Formula One.
Ericsson was ninth in last weekend's Mexican Grand Prix.