1967 GTX, finishing up a restoration on it. Having an issue with the wiring. My windshield wiper motor is not working properly, it will turn on but not park or shut off correctly, I have to almost get the knob in half way between settings to shut off. It is a 915 variable motor that was restored. I am actually getting a shock sitting on the sill plate when I use the switch. All other wiring on the car works properly. I did have the battery negative grounded to the battery tray when I was putting the wiring in, but as mentioned everything seems fine, lights, fan blinkers etc. Battery negative now grounded to engine block and I noticed unless I run a jumper from the negative on the battery to the body of the car I get no power to the car anywhere. That doesn't seem right to me? I plugged a different 915 wiper motor in the bulk head and it works improperly like the one in the car, shock and all. Any help appreciated.