Headlight Relay Harness

Paint, body preparation and modification, interior work and electrical
Post Reply
amwalker
Supporter
Posts: 157
Joined: 27 Jan 2008 13:46
Location: Wellington, CO

Headlight Relay Harness

Post by amwalker » 04 Oct 2013 19:55

Here is my version of a headlight relay setup. I put this together in such a way that I could remove all of the new parts and plug the stock wiring back in without any repairs or modifications. I'll post the schematic over the weekend, in the meantime see here for the list of materials I used.
Image

The improvement of the lighting is subjective without specialized equipment to measure the light output and adjustment, so I just go by voltage drop at the lights. With the relay setup installed, I observed 12.08 volts at the battery terminals and 11.92 volts at the low beam terminal of the driver’s side outer lamp. With the stock setup, I observed 12.12 volts at the battery and 10.7 volts at the common terminal (ground terminal on the connector) of the driver’s side outer lamp. It works well enough for me so I thought I'd share this with everyone. This replaces the Dapper Lighting projector kit I had on the car, only because I'm selling this car and saving the projectors for my other 510.

The key to this setup is the use of the Vintage Connections Non-Latching 6-pin connector. This allowed me to tap into the stock harness without cutting into a single wire. As you can see I even left the stock headlight relay in place. The second picture shows the required jumper wire to pass power back to 6-pin connector.
Image
Image

Once I had a way to use the stock harness I needed a power source. For this I pulled power directly from the battery and ran it through a 4-pin ATO fuse block. It wasn't the ideal way to spread power around, but I haven't had issues yet. A ziptie around the harness will prevent loosening problems if there are any.
Image

From there I mounted my relay bases next to the stock fuse box and began to route my wiring.
Image

Finally, I ran the wiring to each side of the car. The headlight connectors from Del City took care of each headlight assembly and all I had to do was join the wires together and close up the harness.
Image

If you search by the part number, you will see that most of the items from Waytek have a minimum quantity. Some quick math puts this upgrade at $50 for everything you see here, minus the wire. You can easy cut $10 by not using the Nutserts, I like them because it makes the parts easily removable with a reliable fastener. You can also cut the cost further by not using the fancy braided loom, I just like the look. So, for about $30 (no Nutserts or braided loom), you’ll get some increased headlight power.

If you want to try this upgrade but don't want to buy everything due to the minimum quantities from Waytek, shoot me a PM. I have everything in bulk already and will throw the parts in the mail for my cost+shipping.

Adam
71 510: 4-Door, KA swap, Work in progress (Race)

User avatar
Byron510
Moderator
Posts: 11922
Joined: 01 Jul 2003 23:06
Location: Maple Ridge, BC

Re: Headlight Relay Harness

Post by Byron510 » 04 Oct 2013 22:34

Nice job Adam.
I really appreciate your attention to detail in the use of connectors.
I have built a number of parallel harnesses that simply are triggered by the stock harness from a single head light plug. But you took that one step further by utilizing the plug taking out the stock relay - nice work.

Byron
Love people and use things,
because the opposite never works.

amwalker
Supporter
Posts: 157
Joined: 27 Jan 2008 13:46
Location: Wellington, CO

Re: Headlight Relay Harness

Post by amwalker » 07 Oct 2013 06:14

Thanks Byron, that means a lot coming from you.
71 510: 4-Door, KA swap, Work in progress (Race)

User avatar
KlassicMotion
Posts: 49
Joined: 18 Mar 2012 22:49
Location: Was Kansas, Now Alaska

Re: Headlight Relay Harness

Post by KlassicMotion » 15 Oct 2013 15:09

Nice clean install.

So what is it about the old original system that makes it so poor?
Last edited by KlassicMotion on 15 Oct 2013 15:21, edited 1 time in total.
-Kyle

1971 510, 2dr
1971 240Z
1972 SAAB Sonett
1976 Ford Bronco
1977 Honda 400Four SS
2010 Colorado V8
2014 Jeep JKU Willys

"God gave man one brain and one penis, and only enough blood to use one at a time." ~Robin Williams

amwalker
Supporter
Posts: 157
Joined: 27 Jan 2008 13:46
Location: Wellington, CO

Re: Headlight Relay Harness

Post by amwalker » 15 Oct 2013 15:19

Kyle,

The stock wiring has power for the headlights routed through the headlight switch. All of that wiring through the dash and the switch creates a large voltage drop at the lights themselves.

Adam
71 510: 4-Door, KA swap, Work in progress (Race)

User avatar
KlassicMotion
Posts: 49
Joined: 18 Mar 2012 22:49
Location: Was Kansas, Now Alaska

Re: Headlight Relay Harness

Post by KlassicMotion » 15 Oct 2013 15:23

I was wondering if it was the switch that was causing the drop...
Is the difference noticeable at night?

Nice install. Thanks for the write-up.
-Kyle

1971 510, 2dr
1971 240Z
1972 SAAB Sonett
1976 Ford Bronco
1977 Honda 400Four SS
2010 Colorado V8
2014 Jeep JKU Willys

"God gave man one brain and one penis, and only enough blood to use one at a time." ~Robin Williams

User avatar
Byron510
Moderator
Posts: 11922
Joined: 01 Jul 2003 23:06
Location: Maple Ridge, BC

Re: Headlight Relay Harness

Post by Byron510 » 03 Jun 2018 23:14

Adam, or anyone else out there that can help on this subject of this wiring.

I should have asked about the pin out Adam did during this modification. I had done headlight upgrades in the past using the stock relay in place, tripping the aftermarket relays to run a sub harness to the headlights. But I have never omitted the stock relay itself - and it's about time to kill the redundancy.
So this afternoon, I used an old 6 pin female plug and shoved it into the headlight harness. I went through the motions of finding switched power and ground in the 3 positions of the light switch, and switching the HI/Low beam indicator switch on the column. And then realized that if I unplugged the harness from the headlights, I did get a different set of readings. But I can't quite wrap my head around the solution. I know its right in front of me, though, so I ask for your assistance.

My harness is a 69 sedan, not sure if it changes from 69-72 (I know the 68's are unique).

So, this is what I found.
'69 Headlight Relay Harness PIn Out 3.jpg
'69 Headlight Relay Harness PIn Out 3.jpg (171.96 KiB) Viewed 204 times
Now my alignment of the harness plug thankfully is the same as the one pictured here from Adam's post above;
20131004_144220_zps33e4a244[1].jpg
20131004_144220_zps33e4a244[1].jpg (68.71 KiB) Viewed 204 times
So it's clear that pin 3 is doing the switching for the high beam indication (by switch ground from terminal 85). To Me pin 1 or 6 can be used to engage the relay, but I'm not quite sure how this can be done as I already have a switched ground....
I can't make a connection as to how pins 1, 4 & 5 are switching the relay (s) using either a SPDT (Type 2 relay?) or DPDT (Type 1 Relay) - which is the diagram I believe I have drawn in above.

Can anyone sort me out here and provide a schematic that will replace the stock headlight relay with either 1 or 2 standard relays?

Oddly, my new headlight system will employ 4 single filament bulbs in our standard quad light lay out, utilizing a 3rd "hold over" relay to keep the low beams on when the high beams are engaged (if needed). I believe a lot of new cars are wired this way as well. But the new Hella Bi-Focal lights that I am planning on installing in the low beam position use only H1 bulbs unlike the standard H4 twin filament bulbs. The product is billed to be the best of the best for lighting quality, cut off and focal clarity. My aging eyes need the help! We'll see if these are worth the money (which was quite a bit I might add!)

*Edit* OK, I think I figured out pin 4 - It's a 12V source because it runs from the stock fuse box, to the gauge panel through the stock high beam indicator light and is looking fro a ground at the relay when the high beams are switched on....

Thanks for all your advice and help in advance.

Byron
Love people and use things,
because the opposite never works.

User avatar
Byron510
Moderator
Posts: 11922
Joined: 01 Jul 2003 23:06
Location: Maple Ridge, BC

Re: Headlight Relay Harness

Post by Byron510 » 03 Jun 2018 23:24

OK, staring at the post making sure the spelling is correct – I think I just figured it out – correct me if I’m wrong;

2x Type 2 relays used;

For low beam: Pin 2 to Terminal 86, Pin 1 to Terminal 85
For high beam: Pin 2 to Terminal 86, Pin 3 to Terminal 85
Obviously Terminal 30 is full amperage positive 12v feed from the fused source (14 gauge wire - 20 Amp up to 5' long - I require 17 amp with 2x 100 watt bulbs) and Terminal 87 (& 87a) goes to your pair of lights of choice.
The lights then ground to the chassis at a good, solid point - again 14 gauge wire per pair of lights.

Would the electricians out there agree this would work?

No Hold Over relay needed to keep the low beams on when the high beams are engaged.
However I will have a high beam flash in Position 1 of the headlight switch, which isn’t a bad thing (Running lights only with high beam flash - kind of opposite of the low beam flash all 68's had in position 1 on the headlight switch).

I’m still questioning the low amperage signal from pin 4, I’m sure I’m missing something here as I see Adam in the photo above did utilize this pin.

Thoughts?

Byron
Love people and use things,
because the opposite never works.

User avatar
Byron510
Moderator
Posts: 11922
Joined: 01 Jul 2003 23:06
Location: Maple Ridge, BC

Re: Headlight Relay Harness

Post by Byron510 » 05 Jun 2018 11:58

I put some more time into this yesterday - and around picking up kids from sport, taking in the last Scouts group committee meeting of the season and totally leaving my wife to deal with family and dinner - I made some progress.

Since the headlight upgrade will now be a four X - single filament bulb system in that it uses H1 bulbs in both the low beams and high beam sockets, I needed power to the low beam lights in both low beam and high beam at position 2 on the head light switch. And of course the high beams controlled by the combination switch (turn signal/high beam switch) also in position 2.

As you can see by the spreadsheet layout above, either terminals 1 and 6 on the existing harness can trip the low beam lights at position 2, and terminal 3 is the high beam trip. I wired this up last night on as a test and it does work.
If one takes signal switch power (12v) from terminal 2, and uses terminals 1 (or 6) and 3 to trip the signal side of the relay, we have a system. This is what I intended to wire last night. However at some point I had brain fade. Instead of using the 12V switching signal from terminal 2, I used the 12V signal direct from the fused 12V source from the feed side of one of the relays! Now I have high beams in all three positions of the headlight switch, off- park lights and driving lights which was unintentional. I may go back and change this…maybe….

There are 2x 20 fused sources that are independent of each other. A 14 Ga wire is electrically capable of handling 16.66 amps (2x 100/12) up to 5' long, so 20 amps is enough of a buffer. FYI, a 12 gauge would be good for 7.5 foot of length, 10 Ga for 11.5'.
The 14 Ga spec is designed for the high beam circuit running 2x 100 watt bulbs from the stock relay location. The low beam circuit is just a bit overkill at 14 Gauge. You could get away with 16 gauge if you really wanted to.
I apparently went extreme overkill when I wired the car in 2004. I ran the extra wires then knowing I was going to 'one day' do the headlight harness / relay upgrade. When wiring the car originally I was moving the fuse box(s) inside the car (pass kick panel area) and hiding the harness up under the fender and around the bottom side of the rad support. Hardly anyone has ever noticed that the harness is not visible - funny that way. Anyways I ran 10 gauge wire back then, which is good for over 30 amps - or 360 watts - per circuit. So I think I'll be fine as I really didn't feel like running those wires again to a smaller gauge.

This is what the wiring diagram looks like. I spent as much time making this drawing as it too me to make the harness and roughly install it.
4x Single Filiment headlight harness.jpg
4x Single Filiment headlight harness.jpg (96.7 KiB) Viewed 143 times
Now what is missing is my high beam indicator light on the dash. Personally I don’t miss it as there is nothing worse than a blue light glaring back at you off the dash boards when you are peering into the darkness. Legally however, the dash high beam indicator needs to be there. And this is one item I have not figured into the system above – hopefully there is an electrical guy out there that can assist. The drawing below shows a blue broken line from terminal 4 to the 12v + feed from the fuse box.
4x Single Filiment headlight harness 2.jpg
4x Single Filiment headlight harness 2.jpg (101.2 KiB) Viewed 143 times
Behind terminal 4 is power from the cars original fuse box to the dash light bulb and then to this terminal 4 in series. So my question is if terminal 4 was to be connected to the 12v + source before the relay, when the relay is tripped will it engage the dash light? I’m not sure on my electrical theory here.
What I am concerned about is that the dash light circuit, if wired with the dotted blue line above, is now powered by a 10 amp fuse on one side, and a 20 amp fuse on the other, which makes the whole circuit in the stock harness capable of back feeding – which is not good as the wiring isn’t meant to take a 20 amp load, and something could burn if there was to be a problem. The only way I can think of fixing this now is to use a 3rd relay just to trip the dash light. Or I’m thinking a DPDT relay in place of the hi beam relay would also do the trick. I wonder if the guy behind the parts counter would even know what a DPDT relay is….
Anyone have thoughts on the high beam indicator light?

Byron
Love people and use things,
because the opposite never works.

Post Reply