The vice president wore a protective face mask and glasses on his tour of the GM facility in Indiana after facing criticism for not wearing a mask at the Mayo Clinic.
The memorandum directed at General Motors comes as hospitals say they'll need more ventilators to weather the coronavirus pandemic.
GM and Ford aren't about to start churning out ventilators, but their suppliers could make a difference.
Ford, GM and Fiat Chrysler are going dark amid the pandemic.
Currently, the GM SUVs are among the least-efficient new passenger vehicles on the road, and the mileage hasn’t improved much in the past decade.
"Carmakers that have chosen to be on the wrong side of history will be on the losing end of CA’s buying power," tweeted Gov. Gavin Newsom.
The four-year investigation has resulted in charges against a dozen individuals for illegal payouts to union officials.
The work stoppage lasted 40 days and was the longest the auto industry had seen in two decades.
"Roy A. McCombs tragically lost his life today on a picket line standing up for a better life for himself and his coworkers," the union said.
A union council still needs to approve it in order to bring a painful work stoppage to a close.