I'm unable to lift the back seat cushion on my 2000 buick lesabre. i can hear the clamps catching but the seat will not disengage from them. what should i do? i need to get to the battery to change it.

I have a 2001 Buick LeSabre Limited. Pull up on the rear seat cushion along the front edge. The battery is located under the rear seat. Be sure to connect the vent lines to the new battery. This keeps fumes out of the car, and keeps it from corroding the interior surfaces.

Reach down in the bite-line (where the seat cushion and the seat back meet). Pull up on the seat cushion until the cushion raises above the bottom of the seat back. Pull the seat cushion towards the front. There are two metal tabs that are hooked into the front of the seat cushion that holds it in place; unhook these by moving the cushion forward. To replace, reverse the procedure, but make sure the seatbelt recepticles are exposed before pushing the seat cushion down into the bite-line.

I think the seat design is the same as the 1992 LeSabre. If so this is easy. Grip the seat under the bottom front edge next to the carpet and lift straight up. The seat is held in place by a spring receiver so at this point the entire bottom cushion should now be loose and you can lift it out of the car.
To replace it put it in position and press down until you feel it drop in place. Don't bury the seat belts.

The battery is located under the rear seat cushion.
To remove it.. place your hands in the "bite" of the rear seat-back, and the rear seat. Then pull the seat up and away from the seat back. The seat will come loose and the battery can be accesed.

I searched the owner's manual and there was no mention of folding the rear seats down. If you don't have a manual, you can get one here: http://www.extendedgmwarranty.com/owners-manual/buick/1999-Buick-Century.pdf

You can remove the seats following the instructions below from autozone.com.
Rear Seats
SEAT CUSHION

Fig. Typical W-Body rear seat cushion removal

1. Locate and remove the small bolts at the front lower edge of the seat cushion.
2. Pull the tabs on the rear cushion retainers.
3. Remove the seat cushion by lifting up and pulling out of the retainer.
4. Installation is the reverse of the removal procedure. Make sure the retainer tabs are snapped into place. Tighten the bolts to 18 ft. lbs. (25 Nm).

SEAT BACK

Fig. Typical W-Body rear seat back removal

1. Remove the seat cushion as described above.
2. Remove the anchor nuts securing the rear seat retainer at the bottom of the seat back.
3. Grasp the bottom of the seat back and swing upward to disengage the offsets on the upper frame bar from the hangers.
4. Lift the seat back upwards to remove from the vehicle.
5. Installation is the reverse of the removal process. Make sure the hooks on the seat back are properly installed to the hangers. Tighten the anchor nuts to 89 inch lbs. (10 Nm).

The battery is under the back seat. I stand in the middle of the back seat area and pull up on the seat to remove it. Then carefully remove the battery clamps negative first. Remove the battery hold down bolts and lift the battery out.

It should be under the back seat in the passenger side.The bottom cushion hinges forward on hooked anchor tabs at the lower front of the cushion. Take hold of the bottom cushion at the seam where it meets the bottom of the backrest and lift. The bottom cushion will hinge forward and the hooked tabs at the lower front of the cushion will release from the anchors so that you can lift the cushion out of the car.

Rear Bench
(see Figure 4)

1. Bearing down with your knee on the rear seat cushion, push the cushion rearward and disengage it from the retaining brackets.
2. Remove the rear seat armrests if applicable.

Fig. 4: Pull the bottom of the seat upwards and pull out

1. Remove the seatback lower retaining screws and seat belt bolts.
2. Grasp the seatback at the bottom and lift it up to disengage the hanger wire from the retainer brackets.
   

To install:

1. Position the seat back assembly so that the hanger wire is fully engaged in the package tray slots.
2. Install the lower retaining screws and tighten to 13-19 ft. lbs. (17-37 Nm).
3. Position the seat cushion assembly into the vehicle.
4. Apply knee pressure to the lower portion of the seat cushion assembly. Push rearwards and down to lock the seat cushion into the seat retainer.
5. Check the seat cushion to ensure it is secured into the floor retainer.
   

Rear, Fold-Down Seats

1. Push the rear cushion rearwards, then lift to release. Remove the cushion.
2. Remove the 2 lower retaining screws attaching the seat back to the floor.
3. Lift up and disengage the upper clips of the seatback from the top of the folding floor.
4. Remove the seat assembly.
   

To install:

1. Position the seat back assembly and align the retaining hooks. Ensure hooks fully engage in slots.
2. Install the two outboard retaining bolts, then tighten to 13-19 ft. lbs. (17-27 Nm).
3. Lower the seat backs and install the upper retaining screws.
4. Install the lower center retaining screw, tighten to 13-19 ft. lbs. (17-27 Nm).
5. Install the rear seat cushion. Ensure the rear seat cushion front retainers latch properly.

Hope helps (remember rated this).

The battery for the 2000 Buick Lesabre is under the back seat. I stand inside the car at about the middle of the back seat. Using both hands I pull up sharply on the back seat until it comes up. Remove the seat and you'll see the battery. Changing the battery is the same procedure as any battery. Remove the negative battery clamp first, then the positive, unbolt the battery, and lift it out.