Terms were not immediately available.
"I have a lot of calluses," Carr said. "I'm like an old carpenter I've been through it. If you let that stuff affect you, you're not going to be able to do your job. One of the reasons I'm excited about coming here is they protect the quarterback well and they have playmakers on the outside."
Carr had a 58.3 passer rating with just three touchdown passes and five interceptions after replacing the injured Jake Delhomme. Carr was eventually replaced by 44-year-old Vinny Testaverde and then undrafted rookie Matt Moore.
Carr will compete with Anthony Wright and Jared Lorenzen for the backup job to Manning, the No. 1 overall pick in 2004.
The former Fresno State product has played in 82 career games with 79 starts. He started all 16 games four times in his five seasons with the Texans, including the last three.
Careerwise, Carr has completed 1,316 of 2,206 passes for 14,026 yards, 62 touchdowns and 70 interceptions. His career passer rating is 74.4. He has been sacked 262 times, including a record 76 for 411 yards in losses as a rookie in '04.
"I think any player coming into a situation like this has to prove something," Carr said. "I have to work just as hard or harder than the guys there. They've been to the top. They won a Super Bowl. They don't need our help."
Joining the Giants will reunite Carr with quarterbacks coach Chris Palmer, his offensive coordinator in his first four years in Houston.
"I'm excited to meet up with Chris again," Carr said. "That's really the main reason I came up here. He has the best feel for what I'm doing. He knows what's best as far as what my mechanics should be when I throw the football."
"We look forward to working with him on the fundamentals of the game," Coughlin said. "We do have some technical things to work on, but we are anxious to work with him in our program. If we can place him in a positive environment, perhaps he can reclaim some of the things that people saw to draft him in the first round."
Carr had career-high totals of 54 passes and 39 completions in Giants Stadium against the Jets on Nov. 26, 2006. He tied the NFL single-game record with 22 consecutive completions vs. Buffalo on Nov. 19. 2006. Carr has passed for more than 300 yards four times, including a career-high 372 against Minnesota on Oct. 10, 2004. He has directed 11 career game-winning drives in which the decisive points were scored in the fourth quarter or overtime, including one last Oct. 7 in New Orleans.
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