4 Hi Headlight Mod

[Hunttman01]

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Are the wires cut or broke on your turn signals? Or are the bulbs burnt out

sent from the tractor cab

 

[thz71]

Are the wires cut or broke on your turn signals? Or are the bulbs burnt out

sent from the tractor cab

Idk what's wrong with um I can't get um fixed

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[southern_z71_92]

Doing this soon hopefully.

 

[Hunttman01]

Looks awesome with the projectors

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[Spule 4]

If you have upgraded your headlights with relays (one for high, one for low) you can just do with a jump-wire with a diode between the two switched feeds to the relays (#86 on a typical automotive relay).

What you need to do is have the cathode end toward the feed of the low beam relay and the anode end on the feed end of the high beam relay. So when you turn on the low beams, only the low beam relay is activated. If you turn on the high beams, both relays will be activated.

No need to add a third relay.

 

[thz71]

If you have upgraded your headlights with relays (one for high, one for low) you can just do with a jump-wire with a diode between the two switched feeds to the relays (#86 on a typical automotive relay).

What you need to do is have the cathode end toward the feed of the low beam relay and the anode end on the feed end of the high beam relay. So when you turn on the low beams, only the low beam relay is activated. If you turn on the high beams, both relays will be activated.

No need to add a third relay.

Who is using 3 relays? 4 hi only uses one

 

[gordinho80]

I need to rip into my wiring. Something is funky with my headlights.

I have the 4 HI mod done along with HIDs installed with a relay. My headlights come on by themselves. I've tried unplugging the headlight switch to see if that was causing any issues, nope. I have to pull the fuse on my HID relay in order to keep the lights off. But even like this, I have a parasitic draw that kills my battery if the truck isnt ran every 2-3 days.

 

[MinnesotaChevy]

does it have to be 16 or can it be 22

 

[Coveman]

This is a good write up, wish I had seen it beforehand. A buddy just purchased a '99 Tahoe and wanted better illumination. It had been a while since I did this on my own truck so I pieced together how we did it.

Time Estimate:
20 minutes

Materials: (about $12)
1. 1 Relay (with plug-in harness, optional). Relay has 4/5 prongs, with #85, #86, #87 and #30 terminals. These are very common relays for cars. I used a spare SPDT relay & harness that has a fifth terminal (87a) that is not used for this project
2. 3-4 feet 16 gauge wire
3. Flexible Wire Conduit
4. Solderless wire connecters
5. Ring terminals for power and ground
6. Shrink wrap
7. 1 inline fuse

Step 1
Disconnect the battery

Step 2
Look for the wiring bundle inside flexible conduit on the driver’s side fender well near the ABS system. Open the conduit and find the brown and lime green colored wires.

Step 3
T- Connect the vehicle’s brown wire to terminal 87 of the relay

Step 4
T- Connect the vehicle’s lime green wire to terminal 86 of the relay

Step 5
Connect a ground wire to the fender well (there are several existing bolts that you can leverage for ground) and connect it to terminal 85 of the relay

Step 6
Connect an in-line fuse / power wire to terminal 30 of the relay. Use your choice of power source (the underhood relay / fuse block is 12 inches away from where we spliced into the headlight wires on the driver’s side wheel well towards the firewall - we chose to tap the battery power supply to the fuse block)

Tape / shrink wrap all connections and hook the battery back up. You now have 4-high!

Other Stuff:
WIRES FOR SPDT RELAY HARNESS (optional- these were the wire colors on the harness that corresponded to the terminals on the relay- you can just match your wires to the terminal numbers on the relay using female solderless connectors):

30 BLUE fused power source
86 BLACK high beam wire- lime green in OBS trucks
85 WHITE ground to vehicle body
87 YELLOW low beam wire- brown in OBS trucks
87a RED (BLANK for this project)

SPDT Relay: (Single Pole Double Throw Relay) an electromagnetic switch, consisting of a coil (terminals 85 & 86), 1 common terminal (30), 1 normally closed terminal (87a), and one normally open terminal (87).

When the coil of the relay is at rest (not energized), the common terminal (30) and the normally closed terminal (87a) have continuity. When the coil is energized, the common terminal (30) and the normally open terminal (87) have continuity.

For this application, the high beam circuit is activating the relay’s coil and closing the 30 – 87 circuit in the relay sending power to the low beam lamps. Once the high beams are turned off the coil is de-energized and the low beam circuit operates normally.

 

[Spule 4]

Who is using 3 relays? 4 hi only uses one

This applies if you are running the lights already on relays. Using the diode method, no relay is needed in theory, but probably not a good idea to run 20 amps through the dash switch!!!