Installing Headlight Relay Harness

[ramsesosirus]

I am getting a headlight harness, some Autopal H4 housings, and some halogen bulbs in the mail this week.

I can take more pics as I get them.

If someone could be so kind as to help me (us) figure out how to install the harness on a stock 76 280z, I'd really appreciate it!

Here is a pic of the "typical" install of the relay harness.  I know the plug won't plug into the 280z harness.

Should I connect the two powers directly to the battery +, or the alternator?  

Which wires should I splice and to where on the stock harness?  The one on the radiator support?

I thought only one wire would need to be spliced, the headlight on/off switch, but this shows 3 wires....

And the FSM schematic isn't making things very clear as to what I need to do...

Basically the relay system just gets its power from the battery

I also just read that the 280z switches the ground on/off, while the 240 switches the power on/off?  What does this change/mean??

 

I'm working on figuring it out too, but I'd hate to hack up the harness if someone can help!  Thanks

Edit: Got the harness in the mail.  Looks pretty stout.  The relays are 40A.  One single 30A Fuse by the power.  

Looks like the wires that need to go to the car are one black that only comes from the relay to this plug, one light blue that is the other side terminal for the H4 Headlight (low or high beam?), and the other is the white that comes from the single top terminal for the H4 (low or high beam?).

So that means splicing into several of the engine harnesses as per FSM?  I'm assuming a low beam on wire, a high beam on wire, and what is this black wire?  Ground?

Thanks for any advice

 

 

 

 

Edited September 7, 2017 by ramsesosirus
Added photo of real harness

[zKars]

Who's going to break the bad news to this poor gentleman....

Ok, me. THat generic head light relay harness requires to you to get access to the inside of the headlight housings to plug those connectors in between the bulb and harness connector. this requires you cut holes in the housings insde the wheel well which then exposes the inside of the houses to road dirt and water.

There is a infinitely better solution to your head light harness relay system that most here are keenly aware of. Search for Dave Irwin or Zsondabrain user name.

His solution is not perfect for 280's however, it is intended for 240's.  They have different headlight connectors in front of the rad, and so far we haven't found new shells to build the relay harness with to make it plug and play for the 280's. Will take some splicing. 

Edited September 7, 2017 by zKars

[ramsesosirus]

Thanks, yeah I knew I would either have to cut the housing, or splice the lead wires.

I did lots of research on this HL project, and I heard that was an issue for the H4 plug.

The other option is to use ZX housings, which have a large cutout.  But expensive.

After determining that I had to splice one of the headlight leads anyway, since this was apparently designed for a go kart judging by the wire length haha

I have to use the "long" headlight lead to go to the RH light (the short side...) and add about 10' of wire per wire to reach the passenger side.  So I already plan on not splicing the wires until I pull the housings, and not hole saw the buckets.  

I actually kind of liked the idea of easier headlight bulb access since these bulbs sometimes burn out quickly I've heard, but plans always seem to change.

 

I know there is no plug in kit for the later 280z.  My question is does a harness of any configuration exist in the bay that has 3 wires from the headlamp switch (I assume OFF, LO, HI).  Then the black wire that comes from the relay goes to the "OFF" function for the switch.

???

From that, schematic, I can't seem to locate such a harness.  Maybe I'm missing a detail schematic for the HL switch...

I'm just not sure of where (at all) to tie these 3 wires into a harness or multiple harnesses, and where in the engine bay, OR is it under the dash?

I plan to post some pictures after with different Halogen and potentially other bulb types (for testing), since this H4 housing has the exact OEM look, not a clear or flat lens.  

 

I also looked into the HID and LED projects, but both are much more expensive to do right, and upon my research (and engineering knowledge) that each bulb really is specifically designed for a specific housing.  That's just how photometrics and optics work.  Don't want to be blinding other drivers, and don't want tickets for blue lights.  I have, however, wanted to have white light for many years, but the Silverstars were the most I ever tried... which are still quite yellowish.

Well here is the Combo Switch detail....

So we have wires 4,5,6,7 controlling the headlights.  But nothing controlling the Off function?  Or is the "O" meaning open, and it's closed unless there is and "O" in the box?  And they're obviously (Calling @Captain Obvious , giant Z logo spotlight in the sky to call for assistance) must be another/more harnesses down the line for the HL.  Hopefully they all conjoin the a single harness of 3 wires.

EDIT: Upon further review of the schematics, it appears that wires 15, 16, 18 actually control the headlights, and the three are in the 3 wire connector as shown.  It is a square-ish connector.  Is the "round" connector further down the line?

Where do these wires go to further down the way, like in the engine bay?  This doesn't specify their colors either...

Edited September 8, 2017 by ramsesosirus
more

[zKars]

Good to know you've done your homework on the options.

In my opinion is it un-necessary to involve or attempt to modify any aspect of the existing wiring. It has been well shown now with many hundreds of installations that accessing the head light circuit at the head light connectors is the "best" solution. No need to touch wiring or decipher schematics for any other part of the system short of a simple cleaning of the headlight switch contacts inside the combo switch assembly. 

Just seems like trying to get that generic harness to work is more trouble than it's worth? 

Yes, for the 280, this presents a problem due to lack of connector options. I've been working on a solution on and off for this and have a proto type, but time constraints have prevented me from acting on this. Maybe this winter. Just because the shells are availble doesn't mean secure connections cannot be made by "other" means...

 

[ramsesosirus]

Thanks for the reply.  

48 minutes ago, zKars said:

In my opinion is it un-necessary to involve or attempt to modify any aspect of the existing wiring. It has been well shown now with many hundreds of installations that accessing the head light circuit at the head light connectors is the "best" solution. No need to touch wiring or decipher schematics for any other part of the system short of a simple cleaning of the headlight switch contacts inside the combo switch assembly. 

I'm not sure what you mean by this, which connectors are you referring to?  (Ones on the radiator support?)

It's really not that difficult to use this harness, I just need to know where (location wise) and what wires will allow me to connect the 3 wires from the generic harness.

Here is the full, detailed wiring schematic.  I've circled what appears to be lights.  I think the bottom one is what I need to find.  If I can find that 3 wire connector with the RB, RW, GB wires, I at least know where I need to tie into, and can then proceed to evaluate connector or splicing options.  (If I am looking at this correctly).  I also have a guy around here who has several "shells" at his shop, I might see if he has extra wiring/connectors to use, instead of hacking my original one(s).

I would like some confirmation from someone @Zs-ondabrain possibly, that I am looking at this correctly.

I do plan on trying to find/track down these wires tonight, by getting under the dash and following them, but that doesn't always work.

Thanks!

Here are 2 pics of Z connectors.  I believe the round one must be the 280z HL connector?  3 wires, one of the terminals looks to be empty.  Are these going to be near the firewall, or inside of the cabin?

Edited September 8, 2017 by ramsesosirus
added connector pics

[Captain Obvious]

What's that?  Do I see a Z logo in the sky??  Haha!! I don't have a lot of time right at this instant, but I'll try to add some quick value where I can.

First, for reading the wiring diagram... The "O" means "makes a connection", and the line between "O's" shows you where that connection is made.

So for example with regards to the headlights... If you look down the OFF column, there are no "O's" because there are no connections. Then when you rotate the switch to the 1 position, there are "O's" in row's 4 and 5 which are connected by a line. This means that "In position 1, wire 4 gets connected to wire 5".

Progressing to position 2, "Wire 4 is still connected to wire 5, and in addition to that, wire 6 gets connected to wire 7."

In English: "When in position 1, your parking lights are on, and when in position 2, your parking lights AND your headlights are on".  That's how that diagram works.

Second, that harness (with some caveats) is truly plug and play. It does not attach to anything under the dash, nor does it plug into any proprietary or unusual connector used just on the 280's. It makes connection to the three prong connector right on the back of the headlight. The intention is that you pull the three prong plug right off the back of the light and connect in that harness instead.

Now for the caveats... First caveat, as you discovered, is that the length of wires between the two headlights need to be long enough to reach from one bucket to the other. If this thing was designed for a go-cart, that may not be the case.

The second caveat is that you need to be able to actually physically get the wires into place, and here's where the Z's are a little difficult because of the way the headlights are physically mounted in the buckets. Problem as zKars alluded to is that the hole in the back of the headlight buckets isn't large enough to pass any of the connectors through.

Your choices are to make the hole in the back of the buckets larger, or to take the contacts out of the plastic connector shells and pass them through the bucket and then snap them back into the connector shells. Not too difficult, and if I was going to use this type of harness, that's probably what I would do.

Hope some of that helps, and if not, I'll mess things up even more when I get more time! 

[Captain Obvious]

" I just need to know where (location wise) and what wires will allow me to connect the 3 wires from the generic harness"

In short... The three wires to connect the generic harness exist at the three prong connector at the back or either headlight. Right there at the glass globe. Inside the headlight bucket. You can't see them without taking the fender liner out and removing the headlight bucket from the back side of the sugar scoop and then taking off the retaining ring that holds the headlight bulb in place.

OK, so not so short?

[ramsesosirus]

1 hour ago, Captain Obvious said:

" I just need to know where (location wise) and what wires will allow me to connect the 3 wires from the generic harness"

In short... The three wires to connect the generic harness exist at the three prong connector at the back or either headlight. Right there at the glass globe. Inside the headlight bucket. You can't see them without taking the fender liner out and removing the headlight bucket from the back side of the sugar scoop and then taking off the retaining ring that holds the headlight bulb in place.

OK, so not so short?

Thanks, great info on both posts.

So, since the "new" relay harness only has one 3-wire connector that goes to the car, do I just plug it into one or either of the OEM headlight connectors?  And then leave the other one "hanging" (taped up)? I would connect to the passenger HL connector since it is closer.  I would have to lengthen the wire (again) so no problem with passing the wires through the bucket housing.  

I suppose I subconsciously knew I would likely have to "make this generic harness work", which is fine since it wasn't nearly expensive as some I've seen.  Wiring is currently my weak point, trying and doing is the best way that I learn.

I already had to splice one of the headlight leads (not nearly long enough...) so I'll pass them through the HL housing.

I'd much rather "hack" or modify the "new" relay harness than the stock.

I also now realize I've been erred in my thinking, the control from the headlight switch would be OFF, Parking Lights, Lights and then the other lever controls HI/LO beams.  

1 hour ago, Captain Obvious said:

What's that?  Do I see a Z logo in the sky??  Haha!!

I thought that was pretty funny myself...

Edited September 8, 2017 by ramsesosirus

[Captain Obvious]

Yup. Plug it into either one and tape the other stock side up. Doesn't matter electrically which side, but you have already correctly identified the better choice of using the pass side (right) because it is closer to the battery.

Good luck, and I'd replace the original 30A fuses with something smaller.  I'd use 20A's for a final value, and I'd even use 10s or 7.5s until I was sure things were working properly. 30 is way bigger than you need there.

Unicorn riding a rainbow unicycle chasing a Z logo in the sky! Haha!!

[ramsesosirus]

2 hours ago, Captain Obvious said:

Yup. Plug it into either one and tape the other stock side up. Doesn't matter electrically which side, but you have already correctly identified the better choice of using the pass side (right) because it is closer to the battery.

Good luck, and I'd replace the original 30A fuses with something smaller.  I'd use 20A's for a final value, and I'd even use 10s or 7.5s until I was sure things were working properly. 30 is way bigger than you need there.

Unicorn riding a rainbow unicycle chasing a Z logo in the sky! Haha!!

Cool, thanks.  Perhaps I was way over thinking this?  

How then, does this make the power come from the battery instead of through the stock system?  Is this just what relays do, controlling where power comes from??  

The new relay harness has a single 30A fuse, you're recommending to use a smaller fuse here?

(Or to replace the stock ones in the panel with something less?  I think the stock fuse panel has 2 10A, one for Left, Right) 

6 hours ago, zKars said:

Good to know you've done your homework on the options.

In my opinion is it un-necessary to involve or attempt to modify any aspect of the existing wiring. It has been well shown now with many hundreds of installations that accessing the head light circuit at the head light connectors is the "best" solution. No need to touch wiring or decipher schematics for any other part of the system short of a simple cleaning of the headlight switch contacts inside the combo switch assembly. 

Just seems like trying to get that generic harness to work is more trouble than it's worth? 

Yes, for the 280, this presents a problem due to lack of connector options. I've been working on a solution on and off for this and have a proto type, but time constraints have prevented me from acting on this. Maybe this winter. Just because the shells are availble doesn't mean secure connections cannot be made by "other" means...

 

Ok, I think you were recommending exactly what the Captain said, to use the actual headlight plug.

Sorry I missed that, makes it much easier and hack free.

That must mean the the stock sealed beam and the H4 halogen bulbs have the same wires in the same place?

Edited September 8, 2017 by ramsesosirus

[Zs-ondabrain]

The sooner somebody makes a matched set of 280Z Headlight connectors (Round, white, 4-position/3-wire connector) the sooner I can make Plug and play headlight upgrade harnesses for the 260/280Z's...

Seems like A LOT of posts and most of it is confusing to those who don't know 12VDC systems....

Grab your inputs from the headlight connector in front of the radiator on the passenger (right) side.
Red = power from fuse box and headlight switch
Red/Black = Low beam (-) wire from Hi/Lo beam switch on the turn signal switch
Red/White = High beam (-) wire from Hi/Lo beam switch on the turn signal switch

Ground the Black or solid Red wire on each headlight pigtail, directly to the frame (clean the metal and bolt down the wire snug)
on the engine harness right side plug....
red to pin #85 on both relays
red/black to #86 on #1 relay
red/white to #86 on #2 relay

#30 on both relays gets fused power from the battery
#87 on relay #1 to the red/black on the headlight pigtail of both headlights
#87 on relay #2 to the red/white on both headlight pigtail on both headlights

Like I said, if somebody can make the connectors AND find the 5mm?? male and female bullets (large bullet connectors on these plugs) then I can make P+P harnesses with no cutting, drilling or hurting the stock harness.

Hope this helps for now.

[Zed Head]

People would probably buy a Cut "n" Play product.  If the relays are common and replaceable, it would be a no-need-to-go-back system.  Permanent.