[OLD MEC]

What year is your Carryall? , looks like fairly late model from your pictures? It must be 12 volts battery voltage but is this a factory wiring or after market? Sounds like a bad ground or power supply problem if ALL lights are out? There should be a ground wire running from outside of each light back to battery minus ( NOT the wiring running inside light housing ). I used to check for ground by using test lights connected to frame and touched to outer housing of light and if it lights you have a bad ground. Check the ground connection to battery minus terminal. Also try taking flasher unit out and put in jumper wire and see if lights come on without it. This would mean not enough resistance to make flasher work.
OLD WIRING CAN BE A PROBLEM.
Good Luck.