Headlamp Relays

Installing Headlamp Relays

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Original Write Up By Jim Lane

Now that winter is upon us and it is going to be getting dark earlier now is a good time to upgrade your electrical system by installing relays to control your headlamps to provide them with the full output of your charging system and in return they will provide you with more usable light output and reduce the chances of burning up the light switch or worse your wiring harness.

I realize some of you do not know too much about electrical so I will make this modification easy to perform.

I made this Plug and Play so you can assemble this on your kitchen table and then take it out to your truck and simply plug it into your headlamp system.

Minimal tools will be required.

Although this is for out 1st. Gen. Trucks it is generic and will work on almost any single headlamp system excluding ones with Daytime Running Lamps.

I promise I will have something for you soon.

I have done the research and know what will work so all you have to do is follow along.

First all headlamp sockets are not created alike, The one in the foreground I bought from Pep Boys and is sold under the Motor-Mite name, it cost around $2.99.

Do not get these, they are junk, but they do have some that are suitable in the section where they have the aftermarket lights and dress up parts for the ricers and wanna-bees.

They are sold under the 3A Racing brand and the part number #469993 @ $8.99 each
They are for the high wattage H-4 lamps and looked to be well constructed and have 14-gauge pigtails, although a bit pricey.

I bought mine at my local truck parts as seen to the right of the cheap one; they are made by Cole Hersee
http://www.colehersee.com/catalog_top/index.htm
And are used on OTR tractors and other heavy equipment.

http://i16.photobucket.com/albums/b38/LaneJ/IMG_7550.jpg
Here you can see the difference in the size of the wire. They look to be 18-gauge wire but since they are from China they would be a metric equivalent.

The ones on my socket are 14-gauge and as you can see quite a bit heavier.

On our trucks the entire Low Beam circuit is 16-gauge while the High Beam is 14-gauge wire.

http://i16.photobucket.com/albums/b38/LaneJ/IMG_7551.jpg
Here you can see the size of the connections to the headlamp.

http://i16.photobucket.com/albums/b38/LaneJ/IMG_7567.jpg

Here is your parts list.

2) Premium grade headlight sockets.
2) 30-amp BOSCH ISO relays. Get the genuine thing, more on this.

8) 12-10 gauge uninsulated Butt Splice connectors. (I bought High Temperature connectors from a HVAC supply)
1) 30 amp self-resetting circuit breaker. (Truck Parts of RV supply)
4) 14-12-gauge insulated ring terminals.
2) 14 gauge insulated .250 male spade terminals.
8) 12 gauge insulated .250 female spade connectors. (Home Depot electrical department.)
3) Small rolls of 12 gauge automotive wire; you will need Red, Blue and Black

Miscellaneous items you will need,
Shrink tubing

Ty-Wraps (zip ties)
Convoluted tubing (Split Loom)

Tools:
Wire cutters.
Good terminal crimpers.
Sharpie marking Pen.

Now we get started, from your rolls of wire you will need to cut.
8 feet each of Red, Blue and Black wire.

Looking at the socket with the wires FACING you, hold it like a “U” or a horseshoe.
The left wire is the High Beam, the bottom wire is the Low Beam and the right wire is the Ground.
It might also be marked on the socket.

Now,
Strip ¼” to 3/16” off the insulation and connect them together to the 3 lengths of cut wire.

Red = High Beam
Blue = Low Beam
Black = Ground
These high temperature connectors require a lot of muscle to crimp but they make an excellent connection.

http://i16.photobucket.com/albums/b38/LaneJ/IMG_7569.jpg
Now that you have made sure they are in the right position and the connection is tight, slide some ¼”shrink tubing over the center of the splice and heat it with a heat gun or carefully use a cigarette lighter to shrink the tubing to the wire and seal it tight.

http://i16.photobucket.com/albums/b38/LaneJ/IMG_7572.jpg
You should have 3 nice looking connections when you are finished and hopefully no burned wires from the lighter that got too close.

Of course if you used regular insulated Butt Splice connectors you will have a lump on each wire, but that is OK.

Straighten out the 3 wires and secure them with ty-wraps or even electrical tape to make a nice straight set of wires. When you get them all even, cut all of them at the opposite end of the socket so they are the same length.
This will be for the passenger side connection.

If you noticed I did use 2 different styles of sockets for demonstration purposes.

http://i16.photobucket.com/albums/b38/LaneJ/IMG_7573.jpg
Now cut yourself 2 feet of the 3 colors of wire and repeat yourself with the other socket making another harness that will be used for the driver’s side connection.

http://i16.photobucket.com/albums/b38/LaneJ/IMG_7576.jpg
Now take the opposite ends of both harnesses and make sure all of the ends are cut straight and then strip them back ¼” to 3/16” and holding the wires in pairs inset both wires into the same side of the Butt Spice connector and then crimp them securely.

Do this for all 6 wires; there should be 3 pairs of 2 when you are done.

http://i16.photobucket.com/albums/b38/LaneJ/IMG_7580.jpg
To the other side of the Butt Splice connector crimp a 6” length of wire the same corresponding color.

Check your connection and then again slip a piece of ¼” heat shrink tubing over the connection and shrink it into place.

http://i16.photobucket.com/albums/b38/LaneJ/IMG_7582.jpg

Next take your 2) 30-amp BOSCH relays and secure them together using a Ty-Wrap or electrical tape.

With a length of wire fashion a jumper and provide a pigtail, this will connect to terminal #86 on both relays using a Female Spade connector. On the end of the pigtail provide a ring terminal, this will be a Ground connection.

This is the WHITE wire in the picture, you should use a different color, you could use Black wire but it should not be Red or Blue for ease of identifying the circuit after it is installed. It is just easier to diagnose later on. If there is ever a problem.

Also cut 2 lengths of 12-gauge wire 24 inches long and secure an insulated Female Spade connector to the end of each one, pair them up and on the other end secure them together into the same Ring Terminal.

This will go to terminal #30 on both relays and will supply the power. This the yellow wires in the picture.

http://i16.photobucket.com/albums/b38/LaneJ/IMG_7587.jpg
Installing Headlamp Relays Part-2


This is how your connections should look as far as we have gone. The White wires are the ground #86 for the coils and the yellow wire supplies the battery power to the armature #30 in the relay.

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Now take the harness you just made and even up the length of the wires opposite the sockets (where you crimped the 2 wires together onto the 1 wire), now secure 12-gauge .250 Female Spade terminals to the ends of the Red and the Blue wires.

When you have this done connect them onto the relays,
Blue wire on to the Right hand relay terminal #87.
Red wire on to the Left hand relay terminal #87

Almost there.
Now take 24 inches of 14-12 gauge Red and Blue wire and pair them up, onto one end of both wires secure a 14-12 gauge insulated .250 Female Spade terminal and on the other end secure a .250 Male Spade terminal.

Note: this wire can be as small as 18-gauge as it is only the trigger and carries minimal current.

Connect this wire to the relays,
Blue wire on to the Right hand relay terminal #85. coil +
Red wire on to the Left hand relay terminal #85. coil +

This is the trigger wire that will interface the relays to the trucks headlamp circuit.

http://i16.photobucket.com/albums/b38/LaneJ/IMG_7591.jpg
After you have all of the connectors where they belong, take your Sharpie pen and carefully designate the terminal number so if you ever have to replace a relay it will be as easy as reconnecting to the appropriate number.

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This is what it should look like when you are finished.

http://i16.photobucket.com/albums/b38/LaneJ/IMG_7601.jpg
This is how you will connect the trigger wire onto the existing drivers side headlamp socket. Once secure fold it back over the socket and secure it with a Ty-wrap

http://i16.photobucket.com/albums/b38/LaneJ/IMG_7600.jpg

Here is a schematic of what you have just done.

You will see I have also included a 3rd. relay to turn on the Low beams in conjunction with the High Beams.

This will simulate you holding back to “flash” when you pull back on the turn signal stalk.

It will burn all filaments at the same time.

Simply add the 3rd. relay into the circuit and connect it where the X is. You will add the circuit in yellow.

When you are finished I would suggest to cover the wiring harness using some split loom to protect it and to make it look professional looking.

When choosing the relays I would use Genuine Bosch and not the cheap generic look alikes, there is a big difference and your headlights are critical to have working.

There is no room for your headlights to go out at 70 MPH on a dark moonless night.

I designed this harness for the relays to be mounted on the fender panel next to the battery.

The harness will pass over the core support to the passenger side headlamp.

Trigger wire will connect to the driver’s side headlamp socket.

Driver’s side harness is bundled with the trigger wires.

Mount the circuit breaker close to the battery and connect to the (+) battery feed.

Secure all ground connections under a clean bolt or screw to clean metal.

Here is your parts list again.

2) Premium grade headlight sockets.
2) 30-amp BOSCH ISO relays. Get the genuine thing, more on this.
8) 12-10 gauge uninsulated Butt Splice connectors. (I bought High Temperature connectors from a HVAC supply)
1) 30 amp self-resetting circuit breaker. (Truck Parts of RV supply)
4) 14-12-gauge insulated ring terminals.
2) 14 gauge insulated .250 male spade terminals.
8) 12 gauge insulated .250 female spade connectors. (Home Depot electrical department.)

3) Small rolls of 12 gauge automotive wire; you will need Red, Blue and Black

Miscellaneous items you will need,
Shrink tubing
Ty-Wraps (zip ties)
Convoluted tubing (Split Loom)

Tools:
Wire cutters.
Good terminal crimpers.

Sharpie marking Pen.

Notes:

Cut yourself a 6” piece of 12 gauge wire and crimp a .250 Male Spade connector on each end.

Stow it away it in your glove box, if your relay ever should fail, connect it to wire terminal #30 and #87 and you will bypass the relay.

Ty-wrap is the same as a Zip-Tie.

This should shed some light on the questions of installing relays.

Let me know if you have any questions.
Jim

--Iker42 21:50, 7 November 2007 (EST)