The Dodgers dropped two of three to the team with the third-worst record in the majors. Los Angeles' NL West lead was trimmed to 2 1/2 games over San Francisco, which won 9-0 at the New York Mets.
''For us to come in and take two out of three to win the series was great,'' Jackson said. ''We came in here against a tough team that had a six-game win streak. It's a hostile environment, playing at Dodger Stadium, because the fans are really into the game.''
Especially after the Dodgers' 12-inning, 5-2 win on Saturday night, which ended with Hanley Ramirez's three-run homer against Blake Parker. Ramirez was 0 for 4 Sunday with a pair of double-play grounders and didn't hit a ball out of the infield.
''After last night, you think that you're going to have a little energy today. That's the only disappointing part about today,'' manager Don Mattingly said. ''It didn't feel like we had a ton of energy.''
Jackson (6-11) allowed two runs and seven hits, struck out six and walked none. The right-hander was 0-4 with a 7.39 ERA in his previous seven starts since beating Pittsburgh 6-3 on June 20 at Wrigley Field.
''I think it was more for the team than myself,'' Jackson said. ''You try to look beyond personal goals and try to be a team player. Our bullpen has been getting taxed, and a lot of it has been due to me not going deep into games.''
Matt Kemp trimmed Chicago's lead to 3-2 in the sixth with his fifth homer in six games and No. 13 on the year. But Cubs first baseman Anthony Rizzo helped preserve the lead in the seventh, making a leaping grab of Carl Crawford's line drive and turning it into an inning-ending double play by trapping Drew Butera off second.
Josh Beckett (6-6) gave up three runs and six hits in four-plus innings in his fifth straight start when he failed to get past the fifth. The three-time All-Star is 3-5 with a 3.30 ERA in 10 starts since his no-hitter on May 25 at Philadelphia.
Beckett, facing the Cubs for the first time since Aug. 28, 2005, struck out Ryan Sweeney with the bases loaded in the third. But he surrendered a leadoff double by Jackson in the fifth, and Coghlan followed with his sixth homer.
''I love playing at Dodger Stadium because of the history and the big crowds,'' Coghlan said. ''You see the ball good, and you're competing against a really good team - which always brings out the best in you as a competitor and as a team.''
''The guys had some really good at-bats and some timely hitting,'' said manager Rick Renteria.
SMELL THE WOOD?
SEEMS LIKE OLD TIMES
Jackson made his big league debut with the Dodgers on Sept. 9, 2003, beating Randy Johnson and the Diamondbacks 4-1 at Arizona on his 20th birthday in a game that lasted just 2 hours and 22 minutes.
Cubs: Newly acquired left-hander Felix Doubront had a bullpen session at Dodger Stadium while continuing his rehab from a left calf strain.
Dodgers: Catcher A.J. Ellis missed his second straight game because of a sore right knee, which was struck by a foul tip off Rizzo's bat in the sixth inning of Friday's series opener. ... Butera was struck in the groin by a foul tip off the bet of Nate Schierholtz on the fourth inning and was given as much time as he needed to collect himself before going back behind the plate.
Dodgers: Their next four games are against the Angels, with right-hander Zack Greinke (12-6, 2.65 ERA) opposing Garrett Richards (11-4, 2.74 ERA) on Monday night at Chavez Ravine. The Dodgers have won only one season series from the Angels in the previous 14 years, going 4-2 in 2006.