Wiring up OEM switch

[Marlin]

Well, I tried using the write up for the switch diagram, only to discover that my foglight switch was not the same as Scott's. I spent a good 1.5 hours with all my switches taking resistance readings and making charts to figure out what leads did what. All said and done, I discovered that the tailgate switch is only a momentary contact, so no go there for wiring up accessories. The cruise switch must have some external input to determine if the switch is open or shut, I would imagine similar to the tailgate switch, only I never got a low resistance reading for any of the lead combinations.
The hazard light switch has multiple possibilities including a off/shut combination and 4 other switched shut combinations. You could do lots with that switch(various lighting setups, fogs/brights roof and so on), only no light on the switch itself.
I used a factory OEM fog light switch from some Isuzu (could have been rodeo or trooper, I have no idea) and a generic 30amp relay that often comes with foglights or can be bought loose for about 6 bucks. Here is the wiring setup I used
From left to right, with the 5th pin being on the bottom right row.
Power for relay and on off light
Cruise switch Blue with white stripe to Fog light switch red with blue stripe

Dash light-
Cruise switch Green with red stripe to same on Fog light switch
Cruise switch Red with green stripe to same on Fog light switch

Power to Relay coil-
86 to Fog light switch yellow
87 to ground (I used the bottom left mounting screw for the glovebox, very convenient and out of sight)

Power to distribution block-
85 to distribution block feeder
30 directly to + terminal of battery with inline 25A fuse

I used 10ga power wire from the battery to the relay/fuse block.
I used 14ga to the CB and monitor and 10 ga for the inverter.

I used the radioshack medium sized project box and it fit perfectly in the glove box with the relay and fuse block inside and left room for the manuals, extra fuses and other junk I keep in there. I drilled separate holes in the project box for the loads and the relay to minimize confusion for future use. I have the CB, ac/dc inverter, and my rear view monitior and camera hooked up to the distribution block, later I will add some foglights. I
All in all I am happy with it. Here are a few pics, I moved my DC power strip as well, still have to run the wires but it got hot outside, time to come inside when you are so hot that your nose starts running.

[LittleBeast]

Yeah I found the diagram from Moncha to be wrong as well, but it is just a flip flop of the + and - I forget I have the diagram somewhere and I will pull it out soon because it looks like I need to redo the wiring again for the 3rd time to get this right.

My problem is the HID in the fog lights will not ignite if the engine is running. If the engine is off then both lights will ignite and stay on and you can then start the engine up and be fine (all lights stay on) however if you start the engine first and then try to turn the HID fog lights on then only the left light will ignite and stay lit, the right one might "try" to ignite momentarily but looks like it never gets enough juice to fully light.

So should I buy another relay and hook up one relay per light?

Or should I redo the ground wire to go to the frame instead of back to the negative battery terminal?

Or should I make both + wires 10gauge and the same length from the 1 relay and make the - ground 10ga as well? What do you think?

[MSHardeman]

Hmmm....When I wired up my fog lights (in place of the round running lights) I used Moncha's auxillary fuse box write up, fog light install write up, and his factory switch diagram and everything seemed to work fine for me. Maybe I got confused at some point and didn't follow his wiring diagram 100% and that's why things are working, and have been for three or more years now.

[Marlin]

Yeah I found the diagram from Moncha to be wrong as well, but it is just a flip flop of the + and - I forget I have the diagram somewhere and I will pull it out soon because it looks like I need to redo the wiring again for the 3rd time to get this right.

My problem is the HID in the fog lights will not ignite if the engine is running. If the engine is off then both lights will ignite and stay on and you can then start the engine up and be fine (all lights stay on) however if you start the engine first and then try to turn the HID fog lights on then only the left light will ignite and stay lit, the right one might "try" to ignite momentarily but looks like it never gets enough juice to fully light.

So should I buy another relay and hook up one relay per light?

Or should I redo the ground wire to go to the frame instead of back to the negative battery terminal?

Or should I make both + wires 10gauge and the same length from the 1 relay and make the - ground 10ga as well? What do you think?

HIDs do not draw much current at all, hence the fact that the factory HID wiring is fairly small (14 or 16ga). One relay would be plenty, those things are rated to 30amps. It sounds like you have some switch issues. It makes no sense that it would work with the truck off and not when its running. What are you using for the power supply to the coil in the relay? Is the relay hooked directly to battery? You should never ground directly to battery, I would move that to the frame. I think its a power to the relay problem at the switch, or you could have a bad ballast, and the vibration of the truck running is enough to prevent enough current for the inductive kick to "ignite" the bulb. That is easy to check, just swap ballasts between the two lights, if the same ballast has the same problem, voila, problem solved, if not, it tends to lead to the ground connection or the switch.

[LittleBeast]

Yeah I thought the same thing about it being one of the ballast, but it doesn't always do it to the same side, it rotates sides and sometimes doesn't do it at all. These are brand new ballast and it did the same thing with the old ballast and I tested those independently and they worked perfectly, and yes I have tried multiple relays. I think I will change out the positive and negative wires and go ahead and ground somewhere to the frame.

[Marlin]

I just thought of something else, check you battery terminal voltage, with the truck running, and with it off. Do the same at the leads to the HID ballast. If you have an electrical issue on the truck somewhere, and the voltage is dropping to say, under 12v at the lights, it may be enough to be on the cusp of volts being too low, hence the intermittent problem.

[LittleBeast]

hmm, interesting thought I will do that the next time it is not working. I have tried everything though and I just bought a brand new battery for the VX 2 weeks ago (Optima Red Top died) and I have tried with and without AMP and other things on, only thing that changes anything is when the motor is running. So maybe altinator issues..... we shall see How hard is the altinator replace? I might just do that anyways, I don't think it has EVER been replaced in 130k+ miles now.

[Marlin]

hmm, interesting thought I will do that the next time it is not working. I have tried everything though and I just bought a brand new battery for the VX 2 weeks ago (Optima Red Top died) and I have tried with and without AMP and other things on, only thing that changes anything is when the motor is running. So maybe altinator issues..... we shall see How hard is the altinator replace? I might just do that anyways, I don't think it has EVER been replaced in 130k+ miles now.

No sense replacing something that works. But that might explain why your battery died.