off road lights trouble shooting, need some help

Anyone out there know anything about DC wiring? I'm lost......
I have a pair of HID offroad lights hooked up to my truck. They have a 30 amp fuse, a relay, and an on/off switch. Their hooked up to my battery for positive, and chassis for ground.
Im trying to hook up a second pair of identical lights....they have the same harness included. First, I tried to wiring right into the harness of the lights hooked up, utilizing their fuse, switch and relay.
They would not come on and stay on, they both flicker but wont turn on. Then, I ran the second harness like the first, and tried turning them on again....same thing, this made no difference.
I recorded this video clip showing what their doing. I open up the lights and made sure the ballasts and everything was secure and connected. It must be something to do with wiring I would think. If it were a defective light or lights, I don't think they both would be flickering on like they are are at the same exact time and then turning off....
I am completely lost on this one....anyone know what going on?......
thanks
here is a video of what the lights are doing...
https://www.youtube.com/watch?v=mF4ey_LYfyQ

So each set of lamps need their own heavy gauge wire to each relay direct from the battery. The control signal for the coils of the relays can be wired in parallel and controlled by one switch. The trick is to have the heavy wires separate for each set of lamps with each having their own fuse.

ok, so I ran the harness separate like you said but still have the same thing happening.....Ill have to double check it again in the day tomorrow....so for sure one fuse and one relay wont run 4 lights? your saying a second pair muct have their own fuse and relay?

also, how do I get them all to run off the same switch? I was hoping by tapping into the other pairs harness I could run them off the same switch. 

You must ground one side of each of the  the relay coils. The other side of each relay coil can be wired together and tied to a 12 volt control switch. So when the switch is thrown, it energizes both relays at once. Each relay contact has it's own 12 volt source from the battery and will energize the lamps individually.

There are a few different ways you can wire them to 1 switch. I'm going to be doing adding 2 more lights to my truck and going to do s a bit of rewiring. Here's a diagram i found online. Hope this helps.

I don't understand why the circuit designer dropped to 14 ga on the return wire. They both carry the same amount of current, I would leave all load wires 10 ga.
So each relay is 30 amps max load. 100/12=8.3x 2 = 16.6 amps per pair of bulbs. So you actually have room for 1 more lamp per relay.

Z66Modder said:

I don't understand why the circuit designer dropped to 14 ga on the return wire. They both carry the same amount of current, I would leave all load wires 10 ga.
So each relay is 30 amps max load. 100/12=8.3x 2 = 16.6 amps per pair of bulbs. So you actually have room for 1 more lamp per relay.

Click to expand...

My thought is that each lamp has an independent ground whereas the 10ga positive feed is shared. Otherwise, I would agree with you on keeping the 10ga if it all ties back together to a common grounding point.

If individual grounds, I can see that. It's just not drawn that way in the schematic.