87 911 turbo Spark problem
 

Ok we own a 97 911 turbo , driving down the road the car just died , to make a long story short it is a spark problem, tried to test the coil, and was not getting 12 volts there. to make another long story short i ran a wire from the positive battery terminal to the coil and the car started right up,took the wire off and the car starts and runs fine, I don't know how that fixed it but the car runs again but i am afraid to drive it in fear of it doing it again, any ideas????????