Cadillac's general marketing manager, Michael O'Malley has left General Motors' luxury division to head the Ford account at the J. Walter Thompson Co. advertising agency.

Mr. O'Malley leaves GM after a year as chief of Cadillac's marketing effort. His departure coincides with GM's $4 billion plan to resurrect Cadillac and formulate a new image for the division. The new look is designed to attract younger buyers to the struggling name plate.

Mr. O'Malley joined GM in 1988 after field and marketing stints with Ford and Chrysler Corp.