I was changing the pads on my sisters TL and she pushed the brake while the caliper was off and the piston fell out. I dont know how to get it back in. Please help. Its the rear brake by the way. TIA

 

did you rember to put the retainer clip cack in that goes between the pads, and did you put the caliper in the slots that it sits in, also you pushed the brake pedal all the way down to decompress the piston.

 

Call an Acura service department and ask a Tech. If I'm not mistaken all you do is put the seals back on the piston and then push it back into the caliper. But call a tech, I'm sure they will help.
P.S. Don't have you sister helping you out next time.

 

you usually dont have to take the seals off.

 

The rear pistons kind of "screw" back in, not just push in like the fronts.