What are codes P0500 P1507 and P1540 on a 1997 Subaru Legacy and how do you repair the vehicle?

Answer 1

I intially posted this question and after messing with the car for quite some time I took it to the dealer. They replaced a ground cable. Basically I learned that any time you have alot of codes showing and you don't think the respective parts are bad you should look for ground problems by checking for voltage drops. In this case I was losing 6 volts between the battery and the body grounding point. The problem was caused by a shady body shop that did body work under the ground and didn't sand the spot before replacing it (to achieve a good contact surface). They also mangled the wire. Once these issues were addressed ALL of the codes went away. Voltage drops can be tested for with a voltage meter. Some shops have more sophisticated equipment but a voltage meter and a little bit of knowledge can save you alot of money. This repair cost my insurance company $180(because it was related to a claim).