1996 Chevrolet Truck signal lights

My problem was left turn signal did not work nor did my emergency blinkers. When I turn on the ignition switch, the left signal indicator to the left of the speedometer is always on. I checked the turn signal assemblies and discovered the bulb sockets had disintegrated. I replaced the sockets. I replaced the ( turn signal, high beam, cruise control, wiper and washer) lever. I replaced the headlight switch. I replaced the combination flasher unit. I now have emergency flashers, right and left turn signal blinkers except when the headlights are on, at which point the left turn signal does not blink and has to be done manually. When one does this, the radio light turns off and both rear turn signals blink simultaneously. The left turn indicator near the speedometer is still always on I used all direct replacement parts from 1A Auto. All wires on the parts were color coded. All parts had the same amount of wires. I do not know what to do next. Please help. Thank you for your time and consideration. Larry Knight