Where do I find a wiring diagram for the jazzy 1103 ?

Here's a link to the Pride Tech Manual guides. Click on the 1103 for a PDF file.
http://www.prideservice.com/TechnicalProductGuides/technicalproductguides.asp

The wiring is pretty simple and straightforward. These operate on a 24VDC system provided by two 12VDC batteries. Power from the batteries goes to the controller into a Joystick/controller combo. It leaves the joystick down to each motor/gear/brake assembly. Power to the batteries comes from the charger which puts out 28VDC, with a 120VAC input. Very rarely does any of the wiring go bad excepting those people who grossly overload the chair, or run it into fixed objects at full speed. Other mishaps with overamping are caused when somebody tries driving over unstable surfaces like sand, gravel, mud/wet grass and spin the motors. This drives the controller crazy because its job is to keep the chair pointed in the right direction, and with wheels spinning, it doesn't know what to do. Overheating the motors or controller, or both. There are two sets of "brushes" on each motor that carry the current from the batteries to the motor. These are located under a black-plastic slotted screw port at the ends of each motor. Removing the plastic screw reveals the brush. It should have a flexible semi-copper lead that shows no evidence of overheating, or brittleness, and should be about 3/4 of an inch long. If 1/4 of an inch, it should be replaced. Check all four. Good luck.