Frazier hit second homer this spring in the first inning off Maholm, who is competing with Josh Beckett for the No. 5 spot in the Dodgers' rotation.
Heisey connected for a three-run shot in the third, his fourth. Maholm was lifted with two outs in the third.
"The two homers were belt-high and over the plate," said Maholm, a left-hander making his third appearance in spring since signing a one-year, $1.5 million contract with the Dodgers on Feb. 8. "That's not really the way I normally pitch. But it's something you do in spring. You're going to have days like this. I've had worse.
"You do it, you learn from it and you do what you can to correct it," Maholm added.
Maholm said he has been told he will make the trip to Australia for a season-opening series March 22-23 against Arizona at Sydney Cricket Ground.
"I'm going and we'll see what the deal is after we get there," said Maholm, who was 10-11 with a 4.41 ERA last season in Atlanta.
The Dodgers played for the second straight day without manager Don Mattingly, who left camp because of a death in his family. Bench coach Tim Wallach was acting manager.
Reds: Alfredo Simon was solid over 4 1/3 innings He allowed one run on five hits and struck out three.
"I feel comfortable right now to pitch every five days," he said. "I just have the rhythm. I was a starter in Baltimore. I just feel real comfortable. All my pitches worked really good." In 19 major league starts, Simon is 3-9 with a 5.15 ERA. Simon might emerge as a starter if Mat Latos is not ready for opening day. Latos had elbow surgery in October and knee surgery in February.
Dodgers: Beckett, who will not travel to Australia, said he expects to make his scheduled start Friday against the Cubs. He was considered questionable Wednesday because of a sprained thumb, he injured in a clubhouse door.
Reds: Latos is scheduled to throw batting practice Friday for the first time this spring. Right-hander Jonathan Broxton, who underwent surgery on his right forearm on August 23, is scheduled Friday for a bullpen session. There a chance he could work an inning on Monday against Cleveland, according to Reds manager Bryan Price.
Dodgers: Matt Kemp tested his surgically-repaired left ankle in center field in a minor league game Thursday for the second straight day. Kemp, who had microfracture surgery October 21, was in the field for two innings. He was 0 for 6 at the plate. ... Wallach said Zack Greinke woke up Thursday after his second spring start Wednesday without further trouble to the right-calf strain he sustained while throwing four pitches in his only other spring appearance on Feb. 27. "He felt good today," Wallach said.
Shortstop Erisbel Arruebarrena, a Cuban defector, arrived Thursday at Dodgers camp, nearly three weeks after signing a 5-year, $25 million contract. He was welcomed by fellow Cubans Yasiel Puig and Alex Guerrero. He grew up with Puig in Cienfuegos. He says he plays with the enthusiasm and energy displayed by Puig, who has been criticized for his flamboyance.
"It's typical of Latin players," he said.
WHAT A DIFFERENCE A YEAR MAKES
Puig hit .517 last spring. He's hitting .176 this spring without a home run. He put in some work in a minor league game Thursday, going 4 for 10 with a homer and a triple.