Few observations.

Diode should go in parallel with your Relay coil (pin 86/85). Something like
http://terpconnect.umd.edu/~toh/ElectroSim/Relay.GIF

It's a good idea to keep the relay as far as possible of the PIC, and not a bad idea to place a 0.1uF + something like 22-47uF close to your relay +12V line. Some also place a small capacitor across the relay coil, and some suggest to install a capacitor across the relay contact (kinda snubber), worth a try.

There's something funky on your design about NPN-PNP connection (at pin 10)

How do you supply the Pos sensor? From your voltage regulator or from the 12V line?

I would suggest you to tie all unused pin to gnd, and set them as input.

Mode switch... i find the resistor setting a bit non standard.

1000uF at the regulator output may screw up most 7805 regulator. You want to keep this value lower than this. Check the datasheet for the brand you're using. Usually 10 - 22uF tantalum + 0.1 uF ceramic do the trick.

HTH