Hello. I have a 1975 B210 with the a14 engine manual trans. I parked it for lunch the other day and it would not start afterwards. In messing with it, if I turn the ignition switch to start, the car will turn over and start. Once I let off of the switch, it promptly dies. I can start it and turn the switch to disengage the starter and it will continue to run but once I completely back off of the switch to the run position, it dies. On the wiring on the back of the ignition switch, I have no power to the Yellow/Black stripe wire or the Black/Red stripe wire when the ignition switch is in the run position. The wiring Diagram shows the Yellow/Black stripe wire goes to the Interlock Relay. I can't find this relay and I think this is the problem. Any help locating this relay or figuring out the problem would be greatly appreciated.