Ford Motor Co., Dearborn, Mich., today said it will contribute another $1 billion to its defined benefit plans before the end of the year, reducing its unfunded pension liabilities to $3.4 billion. The defined benefit plans, with $33.2 billion in assets, had liabilities of $5.9 billion at the end of 2002. Brenda Hines, a spokeswoman, said the company already contributed $2 billion to its defined benefit plans this year. Combined with a year-to-date investment return of 20.9% for the defined benefit plans, Ms. Hines said the plans' funded status will increase to 91% at year end, compared with 83% as of Dec. 31, 2002. As a result, Ford will not be required to make mandatory plan contributions until 2008, Ms. Hines said.