2007 Toyota sienna sliding door cable system broke and the cable came off the motor pulley.

SOURCE: The sliding door handles of my 1998 Toyota Sienna have both broken.

I replaced both of my sliding door handles this weekend. It was actually pretty easy. Cheapest I could find the handles was a little over $70 each. The interior panel is held on with one screw and 10 nylon clips. The one screw is in the cup holder. Put you hand in the cup holder and push out at the bottom. It pops right off exposing the one screw. I started on the clips from the top at a corner. Seemed to be the easiest place to slide a screw driver under. Once I got the screw driver in, I started working my fingers under the panel. The clips run mostly along the top and bottom about 6 inches from the edge. I made an effort to apply the force as close to the clips as I could to reduce flexing the panel. Once I got the first clip to pop out the other followed pretty easy and the panel lifted right off. Carefully peel back the plastic barrier. The exterior handle is held on with two 10mm bolts. Connecting the short cable was pretty obvious once you could see everything. Now I have to teach everyone to open the side doors very gently! Hope this helps.

SOURCE: Rear door

Here's a link to the detailed instructions for this repair. It's not too difficult, just a little tedious dealing with small parts.
Good luck!

http://www.findonefindall.com/toyota-sienna/siennareardoor.htm

SOURCE: both manual sliding doors on my Toyota Sienna will not open

If you can remove the inner door panel you will see a maze of cables running to the various locking points on the sliding door. If the cable going to the FRONT latch on the sliding door is broken (or in my case, simply dislodged inside the door) the door acts as if it is frozen shut.

The front cable is short, and easily replaced even by a newbie mechanic.

SOURCE: Toyota Sienna Power door - SAME THING

Here is a fix on a 1999 Sienna power door cable

SOURCE: the sliding door on my 2004 toyota sienna won't close

Try this.....Find the latch on the door, stick your finger in the hole, lift up and pull the door handle at the same time, the inside latch mechanism should go up, then try the door again. It would be nice if that's all it was huh? Sometimes they stick when they get too cold. If this works for you....spray it with some WD-40 or graphite. Hope this worked for you. Cheaper than the 2000.00 motor!

Bryon