Simple Headlight Upgrades

[markeb01]

Here are a couple of reasonably simple upgrades for the headlight system in our trucks. There are many threads on the internet explaining relay installation; it seemed time we had a thread of our own. First is the installation of relays, next is a jumper that keeps the low beams on normal brightness during the high beam cycle, providing more effective lighting.

In the OEM headlight circuit power runs from the battery to the headlight switch, to the dimmer switch, and out to the lamps. The high beam wires are 14 gauge, low beam 18 gauge and the grounds are 20 gauge. Due to the distance traveled and small 18 and 20 gauge wires in the circuit there is a substantial amount of voltage drop. The result is up to 30% reduction in potential light output. The switches also handle whatever amperage the bulbs draw (generally up to +/- 20 amps), which increases if halogen (or larger) bulbs are installed. Over time this can lead to switch failure, or melted wires – especially with higher amperage bulbs.

With the relay system, the high amperage draw is handled by the relay, direct from full battery voltage right to the lamps. The switches are simply used to activate the relays. It is imperative a fuse or circuit breaker (30 amp recommended) be installed in the main feed wire to the relays. From what I’ve read the amperage flowing through the switches is reduced to something less than one amp. I included a two wire connector after the relays, to allow removal of the grille with the headlight harness intact, similar to the OEM setup. The relays are mounted under the driver side air deflector, so the installation doesn't have to show even on a restored truck. Here they are exposed and covered:





The small relay to the left is for the fog lamps. The other two are for the low and high beam circuits. The headlight relays are mounted on an ABS panel for proper positioning and easy access.

The increase in light output is substantial and remains constant, no longer dimming and increasing with engine rpm. I recommend rewiring the stock headlight harness with 14 gauge wire, since I don’t trust 18 and 20 gauge wires for something as important as headlights. I'm also a fanatic on grounds, and never depend on sheetmetal. All grounds are carried by wire to a common ground, which connects to the engine block.

Following is a wiring diagram for a 4 headlight system. For a 2 headlight system, simply delete the two high beam headlamps from the schematic as both high and low beam filaments are contained in the same lamp.



The second improvement is a jumper harness that redirects the source of low beam power from the dimmer switch to the headlight switch. Under high beam conditions, the normal low beam filament goes out, and a dim filament in the bulb illuminates along with the high beam lamps. The jumper keeps the normal low beam filament illuminated anytime the headlight switch is on, regardless of the dimmer switch setting.

You can buy this jumper from Ron Francis Wiring for about $15.00:

http://www.ronfrancis.com/prodinfo.asp?number=BJ%2D2

Or - if you have the spare parts available in your electrical stash, a free version can be assembled using the following diagram:

[jason65]

I hooked my headlights up to relays. It's a good upgrade.

[SCOTI]

Thanks for sharing this very useful info!

[Vernski]

Hey Markb thanks for the headlight info, works great....Vernski

[Tx Firefighter]

Every truck I build gets the headlight relay mod.

[gabe1004]

I need to know how to re-wire my 1962 LWB C20. Can not find a old harness worth the
money. Wish I could find the complete harness. Anyoone have a clue about starting this project from head to toe. Appreciation for help.

Thanks,

GABE New Mexico

[astrochimp]

I just did mine with relays and H4 lamps.

One change I would suggest to the diagram above is a separate power/fuse for each relay.

Then IF you would blow a fuse, you should still have power to the other beams, and not lose all lights.

I also used circuit breakers.

David

[gabe1004]

do u have a list of items i would use

gabe

[sshockr]

Mid 80's FWD Chevy's have wonderful weather pack relays bolted to the firewall.

[KroAutomotiveInc]

easy worked amazing

[FreakyMalo]

This relay setup works great!

I've found it much more economical to use a diode from Radio Shack instead of the Low Beam Jumper Harness shown above. All you have to do is add the diode between the #85 terminals on the relays so that the current flows from the high beams to the low beams.

These should work. Less than $2. for twice as many as you'll need.
http://www.radioshack.com/product/in...ductId=2062578
The stripe on the diode points 'downstream' so put it closer to the low beam relay.

My setup looks similar to Tx Firefighter's pic. The diode runs between the connectors where the wires go in. You can remove the terminals from the plugs by inserting a pin into the plug and depressing a tab on the terminal. I soldered the diode to the proper terminals, then reinserted them into the plugs, making sure that the tabs were seated so the terminals wouldn't pull out again.

[ChiefRocka]

I did a write up on this a while back ...

[ChiefRocka]

Here's a list of them in FAQ'S:

http://67-72chevytrucks.com/vboard/s...d.php?t=397695

[theastronaut]

There's a good bit of info on doing the actual harness/headlight upgrade on here, but not many pics to show the outcome so you can see the kind of difference it makes.

Here's a shot from the driver's seat showing the low beam pattern of my Cibie Z Beams (7" H4 bulbs) running 80/100 watt bulbs and an upgraded harness with 50 amp relays and 10g wiring straight off the battery. The lights are in my '64 VW bug that has the sloped, inset headlight housings that slightly limit the width of the beam pattern. The beam pattern would be wider in a truck.






Couple of shots of the lights in our '97 S10 with 150mm Hella H4's. Same style harness as above, and same Hella 80/100W bulbs. These have a very crisp cut off pattern on low beam. The light is also very "clear" with no added color, either yellow or silvery blue. Just clear. Notice how the Camry in front of me has a dimmer and more poorly aimed beam pattern. The Hella's have a high beam pattern that is more spread out than the Cibie's, so they don't have quite the reach that the more concentrated Cibie's have on high beam.

Camera brighness set to adjust to brightest area in this pic, the pic is clearer this way but doesn't show the true brightness of the lights as well.




The brighness is set on auto on this pic. The wall is lit up just like that in real life, but the camera couldn't adjust to the light on the camry's bumper so that looks too bright in the pic.

[LostMy65]

There's a kit being advertised in the classified section.
I've also read some here recommending the LMC kit.

Any other recommendations on kits?
Posted via Mobile Device

[theastronaut]

I made my own relay harnesses using parts from Ray's Automotive in Marietta Georgia. He sells melt-proof ceramic H4 connectors, 50 amp dual 87 relays, and relay socket kits. Or he sells pre-made harnesses.

[piratexpress1369a]

Originally Posted by theastronaut

I made my own relay harnesses using parts from Ray's Automotive in Marietta Georgia. He sells melt-proof ceramic H4 connectors, 50 amp dual 87 relays, and relay socket kits. Or he sells pre-made harnesses.

can you post a price on that stuff

[waspp]

Great info! That will be a add on mod for sure. thanks

[theastronaut]

Originally Posted by piratexpress1369a

can you post a price on that stuff

It was around $50 bucks for everything in the pic. His email is: raysautohlpc@aol.com

[piratexpress1369a]

Originally Posted by theastronaut

It was around $50 bucks for everything in the pic. His email is: raysautohlpc@aol.com

thanks for that

[Ta2Don]

Awesome write-up and added info... Bookmarked...

[ABX131]

Are these relay units a universal item? Can I just go to an Autoparts store and ask for these? The relays appear to be the same and used for either low or high beam applications.

[markeb01]

Bosch seems to have the reputation as the standard by which others are measured, but in my experience they are all pretty much the same except for price. Shopping around can establish ridiculous variances in the amount charged. It's easy to acquire everything needed for a few dollars, or over $100 for the same items. The same is true for the receptacles. The only ones worth decent money are the porcelain versions that don't melt under high loads/temperatures. I've also seen many installations that don't use receptacles at all, just female spade connectors on each individual spade terminal.

Also beware that some 50 and 70 amp relays have oversize spades and require oversize special terminals that may be difficult to find if they don't come with the relay.

[McCoyAZ]

It's way easier to just buy the complete harness made by VH Coachworks in the parts section on this board.

Simple to install and well worth the money if your time is worth anything at all.

[rideblue00]

Thanks McCoyAZ, i was thinking about buying his kit.