76 gmc pick up turn signals

I need to wire a toggle switch to work my turn signals.I can get the front signals to work but not the rear.There are eight wires runing to my stearing wheel.they work the turn signals hazards and horn.there are three hot wires,one for the horn and two for the signals and hazards one of which is a lower voltage and remains hot with the key off.The third one is only hot with the key on.I have isolated the left and right front signal wires and if i connect them to the low voltage line they work the front signals and the indicator on the dashboard.but if I connect the lowvoltage wire or the third wire to any of the remaining three wires it blinks both rear blinkers and don't blink the indicators.

any suggestions or wiring schematics would be greatly appreciated.

Thanks. Drewster.