Prosecutors have said someone in the vehicle threw a gun out the window, and another gun was found inside the vehicle.
Combs and his bodyguard, Anthony "Wolf" Jones, have pleaded innocent to weapons possession and bribery charges for allegedly asking their driver to claim one of the guns.
Sgt. Jack Konstantinidis said he followed the vehicle for 11 blocks after it sped from a Times Square nightclub on Dec. 27, 1999, and finally forced it to stop.
Under questioning from Combs' attorney, Benjamin Brafman, Konstantinidis said he did not see anyone throw a gun out a window and the vehicle's windows were closed when he stopped it.
Inside the vehicle were Combs; his girlfriend, singer-actress Jennifer Lopez; their driver, Wardell Fenderson; and Jones.
Prosecutors say Combs and Jones offered $50,000 to Fenderson to claim ownership of the gun after they were taken to a police station.
But Konstantinidis testified he could not hear their conversation.
Prosecutors say Combs' protege, rapper Jamal "Shyne" Barrow, shot and injured three patrons at the club after an argument in which another man allegedly threw money at Combs. He has pleaded innocent to attempted murder.
Lopez and Fenderson, who has filed a $3 million lawsuit against Combs, are not charged with anything.