Electrical systems for vehicle safety harness

Claim 1

An electrical system in a road vehicle, comprising in combination: a starter motor, a manually operable switch for energizing said starter motor, a solenoid which when energized operates said starter motor, a normally closed relay contact between said starter switch and said solenoid, a relay winding for opening said contact, a battery, first and second supply lines coupled to said battery, a first control network connecting said relay winding between said supply lines when the driver''s seat of said vehicle is occupied and the driver''s seat belt is not fastened, and a second control network connecting said relay winding between said supply lines when the passenger''s seat is occupied and the passenger''s seat belt is not fastened, each of said first and second control networks comprising a seat switch which is closed when the associated one of said seats is occupied, a seat belt switch which is opened when the associated one of said seat belts is fastened, a first transistor having its collector/emitter path in series with said seat switch and said relay winding between said supply lines, a first resistor connected between said seat belt switch and the base of said first transistor, said seat belt switch when closed rendering said first transistor conductive so that said relay winding is energized when said seat switch is also closed, and latch circuit means connected to the base of said first transistor, rendering said first transistor conductive if said seat belt switch is opened before said seat switch is closed and comprising second and third transistors having their collector/emitter paths in parallel circuits between the base of said first transistor and one of said supply lines, and their bases connected in said parallel circuits so that said second and third transistors are both conductive or non-conductive simultaneously, each maintaining the other in its conductive or non-conductive state, a capacitor connected between said seat switch and the base of said third transistor, and a diode connecting said capacitor via said seat belt switch to said one of said supply lines.