Weird electrical problems

[BUDDY]

OK Fellas, I need help on this one. I am doing a complete re-wire on my truck and I came up with this brilliant idea of using 6-way plugs, (like what you'd use for trailer lights), for the transition through the firewall for everything, headlights, taillights, marker lights and eventually the starter and HEI. Seems everything is going great, headlights turn on marker lights turn on, turn signals work at the RECEPTACLE on the firewall. HOWEVER, when I plug in the plug, (for the front harness), to the receptacle, the flashers or turn signals will work, but AS SOON AS I turn on the marker lights &/or the headlights, the flasher stops. I am really confused and I have checked and re-checked my connections to make sure they are good and not crossed.

I have it wired as follows.

RT - right turn (green(rear) & dark blue(front))
LT - left turn (yellow(rear) & light blue(front))
TM - marker lights (brown (both))
ST - High Beams (light green)
AC - Low Beams (tan)
GD - Horn

I have an idea that the plug may be getting overloaded, and causing some problems, which I might remedy w/ a relay in front of the receptacle to step down the current into it and then another relay under the hood to step it back up for full voltage to the lights, but that's a LOT of unneccessary connections I think. It may be the only way, but I hope to get around this some other way. I'm really at a loss at this point.

If any of you guys has ANY idea about why this would be happening I'd love to hear from you.

thanks in advance,

Buddy