Is there a way to block 12 volts oneway but allow gnd to flow when applied as to complete the circuit. This is basically what I have. I am using a 12v relay pin 86=12v and pin 85=gnd. I want to be able to block 12v going over thru the relay coil and on to pin 85. I need to find a way to block it between pin 85 and the gnd source. Any help would be appreciated.