I would wire it so all of the marker lights run off of the relay. As mentioned, the switch and plug for the headlights and markers is a weak point.
On my 86, the wire to the factory cab lights runs up the drivers rear door post. I think you may find a wire that is hot with the lights on already run to that corner near the floor. I would also go with a 20 or 30 amp relay even though 15 should be plenty.

 

Thanks for the diagram!

 

Yeah, I was looking to do the same thing. I looked at it last night though, and I was afraid to splice into that park light because the bulb (2 filaments, regular + bright one for turn signal) turned one filament all the way off when the bright one lit up for turn signals. I was afraid that one wire was losing power (for low light filament) every time the turn signal was on. I didn't cut into the wires to test them. So my fear was that if I spliced into the regular (low filament) park light power, I would have my clearance lights all blinking on and off.

The bulb has 3 wires to it. Based on what I just said, that could be the case if two of them are power (hot) wires. But, it could be that there are 2 ground wires and one hot wire, and the filaments are just controlled by which one's grounded. If this is the case, it should work fine to hook up my clearance light relay off of there. Do you know which of those wires right at the front drivers side parking light it what I need to tap, and if it's setup like I just said?

 

If you want to take some of the load off the headlight switch, why not wire a relay to the headlights? That's where most of the load comes from anyway. No need to hack up or splice wires and make a mess when the factory provides what you need anyway. Plus, with a relay on the headlights, you'll get more output from greater voltage.

 

Not looking to take any load off the current system. Just need to install a new relay (with it's own power source) to run off the the same circuit as the headlights/park lights so that they turn on with the same pull switch.

 

I want to run stuff very similar to yours. I've got the lights for the front grille like you (bought them yesterday), and I'm going to put on roof lights or visor lights. Plus, I may put some small tail lights on my tool box or on a headache rack.

 

I just went and looked and its the middle wire of the 3.

 

The wires at the turn bulb are two hots and one ground wire.
The Brown one is the one you want.

 

Thanks for doing that for me! I'll try to get the grille lights hooked up tonight. I already made up the wiring for power and ground for them (a bit of soldering and heat shrinking bits of wire so I only have to run 1 wire to power and 1 wire to ground for all 3 lights).

I'll post a pic after I get it done!

 

Cool goodluck

 

Got the grille lights on this afternoon/evening. Got everything wired right!

 

Love the look. Thats why i did it to mine. Youve got a great lookin truck

 

Thanks! I really like the look too. Can't wait to get roof lights on it!

 

Ended up making this so that I could wire more small things into the same relay:



Then I added floor LEDs inside the cab: