How to wire up the 4-HI mod.

Lots of people have been asking where to buy a kit so I figured;
Forget the kit! If your handy with a soldering iron, make your own!

This particular setup is for a stock harness, no HID relay. If people want, then I can writeup the instructions for that setup too.


Tools required:
wire stripper
diode - Should be found for free from any computer store - ask for an old dead power supply - each one has four perfect diodes.
soldering kit
black tape


Here is a wiring diagram of the existing harness.

Gives you an idea of what to look for. This diagram shows where the diode goes.


Step 1) Carefully remove the two light bulbs from the drivers side. Don't touch the bulbs themselves.

Step 2) Strip back a little insulation from the positive side light green wire on the high beam harness. Don't cut the wire, then you have to put it back together, but just strip back the insulation back a little bit, a 1/2" is good, but a 1/4" inch would be ok.

Step 3) Same thing with the low beam tan wire.

Step 4) Wrap the lead of the diode with the silver band around it around the bare tan wire (lows).

Step 5) Wrap the remaining lead of the diode around the light green bare wire (highs).

Step 6) Turn on your headlights and make sure that the lows are working by themselves, and when you flip over to the high beams, then the lows should have stayed on as well. If it's ass backwards and the highs are comming on with the lows, then flip the diode around, Silver band pointing towards the lows. Turn your lights off, and continue.

Step 7) Solder those two points to ensure a good solid connection. (This step can be skipped, but if you live anywhere with salt on the roads, then skip this at your own peril!)

Step 8) Wrap up everything in black electrical tape.

Step 9) Carefully put the light bulbs back into their respective place in the headlight assembly. Be carefull to not touch the bulbs again. Possibly use gloves or tissues when handling the bulbs.


That's it, enjoy!


Well, in theory after the mod, the high's may not be as bright as before the mod, but a good relay kit on either the lows or highs will resolve that. Most HID kits have one already.

Please post up the instructions that include the HID relay. Thanks!

ackdog said:

Please post up the instructions that include the HID relay. Thanks!

Click to expand...

Ok, just give me a bit of time. There are no pre-made wiring diagrams for this that I could copy and paste from. I have to make up some more 'art' type wiring diagrams in paint... hehe

i have hids and i wired it jus like above and they flicker like not gettin enough juice works fine with stock bulbs...if theres a way to do it would love to no!

young_2010_chris said:

i have hids and i wired it jus like above and they flicker like not gettin enough juice works fine with stock bulbs...if theres a way to do it would love to no!

Click to expand...

Ya, I was hoping that they wouldn't, but I've heard that HID's will flicker if they don't get enough voltage, and by running the four hi mod with no relay it does drop the voltage, but I wasn't sure if it dropped enough to cause flicker. Sorry.

So you need to add a relay to the low beams which is where most people have their HID's. I'm going to write this up as a new install. young_2010_chris, you can just make the your existing wiring match this, and It'll be ok.

Here is my 'art' wiring diagram made up in paint.


Tools you will need;
30amp relay like the one found HERE.
30amp circuit breaker like the one found HERE.
basic electrical wiring kit - including soldering iron, terminal end connections, etc.
Diode - available from any computer store.
Phillips screwdriver.

Both low beams are fed from one single tan colored wire as the source on one side of the truck(I can't remember what side, sorry.) The tan wire feeds one low beam light, and then goes to the other side of the truck and terminates at the second low beam. We will need to be cutting that tan low beam, but it has to be cut before it feeds the first side, otherwise only one low beam headlight will come one. Because I can't remember which side of the truck has the source feed, we will need to take out the signal lights on both sides to see which side has two tan wires going to the low beam.


Phase 1) Get the RELAY ready.
Step 1) Using a ring terminal end, attach a wire to the 30a AUX post under the hood in the relay center.
Step 2) Run that wire to one end of the 30amp circuit breaker.
Step 3) Attach another wire to the other end of the 30amp CB.
Step 4) Run that wire to terminal #30 of the relay kit.
Step 5) Attach a ground wire from terminal #85 to ground.

Phase 2) Get ready to install relay kit.
Step 6) Remove the signal lights from front grill with phillips screwdriver.
Step 7) Determine which side of the truck has two tan wires going to the low beam bulb.
Step 8) Determine which of the two tan wires goes to the other side of the truck. Leave that one alone.
Step 9) Cut and strip off 1/4 inch of insulation on both sides of the newly cut tan wire.
Step 10) Run a new wire from the tan wire that goes to the headlights to terminal #87 on the relay.
Step 11) Run a new wire from the tan wire that goes to the truck headlight switch to terminal #86 on the relay.

Turn on the low beams, they should both be coming on right now with no flicker. If the lows come on ok, at this point you can start to solder your conections, including the relay terminal ends. You can skip this step if you don't have salt on your roads in the winter, otherwise you should be soldering.

Now you can follow the first set of instructions to add the diode. Basically the diode has to go from the light green high beam wire to the tan wire that goes to terminal #86 on the relay with the silver band pointing towards the tan wire.

This is how I have wired up my HID's. No flicker, and they stay on when I flip to high beams.

good wright up!

Pardon the ignorance. What does this mod do?

makes the high beams and low beams all come on when you put the high beams on. all "4" on when "hi" beams on. currently they are independent, lows or highs on at a time. and if you put HID headlights in your truck, on both low and high beams, when you click on the high beams, it takes a few seconds for the high beams to "glow up" and it's like turning your lights off basically for a few seconds. doing the 4-hi mod leaves the low beams on and keeps the road lit up while your high beams catch up. just did it the other day and i like it a lot more. plus you have extra light with the low beams on as well as the high beams. nice and bright.

THIS is the write-up I've been looking for! Thank you SO much 99yuk, yur tha' man!
In another post he also said that the diode needed to be a 10amp (max surge)....can we sticky this?

I finally got around to doing this yesterday
I tapped the wires from the flex loom just inside the drivers side fender and soldered the diode in, already had relays because I used the HID kits for both hi's and lo's.

These are the diodes I used from Radio Shack (thanks 99yuk)

Here's where the wires to the Hi and Lo beams are located

Light green for Hi, tan for Lo, band on the diode should be facing the tan wire

Heat shrink it all, don't forget to put the heat shrink on before you solder

Ta-dah! Hi 4, This forum rocks! Thanks again for posting this up 99yuk!