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Putting headlights on relay...

27K views 94 replies 17 participants last post by  MMMM_ERT 
#1 ·
Where's the best place in the factory wiring to install a relay for the headlights?
Somewhere along the light blue wire from the dash switch, or the orange power wire from the fuse panel?
Or maybe out on the core support and run wiring to it?
 
#3 ·
That's an option, but I've already got a fused relay half-wired...
That sort of answers my question though... sounds like putting it in-line between the switch and fuse panel works. I just don't need to fuse Pin 30 if I do it that way.
Sound right?
 

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#4 ·
#7 ·
Scott's diagram is what I did using MAD's schematic. The only thing different is I used a separate fused wire (fusible link) for each relay. I mounted them on the radiator support and took the power from a junction block I supplied power to from the alternator via another junction block on the firewall. This way you can avoid having to pull power from your battery +ve terminal and you are getting full power directly from a regulated source. You can take it from the buss bar as well but if you have electric fans, a/c, etc. this is a good solution to avoid cluttering up the buss bar. Great upgrade btw, my headlights are nice and bright now and you don't have all that amperage going through your dash.
 
#11 ·
Any of those diagrams will provide the system you'd need.
Just variations on the theme ...

You want the relays as close to the headlights as possible.
I usually mount behind the rad. support on the drivers side to allow for easy pickup of the coil source power (original headlight feed(s)).
On some systems (highdraw offroad stuff) I use one relay per lamp.
One relay per mode is plenty for 90% of street applications.

And :yes: ALL ISO/CE/ANSI/IEC relays have the contacts universally numbered - dependent on the relay type and function :thumbsup:
 
#12 ·
FWIW, you can buy an entire conversion harness with relays and everything for under $40 that comes with new plugs. Just connect to battery and ground, unplug original headlight plugs, plug ONE original plug into new harness, plug new harness plugs onto lights, and done. No cutting and easily reversible.

 
#13 ·
FWIW, you can buy an entire conversion harness with relays and everything for under $40 that comes with new plugs. Just connect to battery and ground, unplug original headlight plugs, plug ONE original plug into new harness, plug new harness plugs onto lights, and done. No cutting and easily reversible.

That is as cool as a roller cam!
 
#16 ·
Stiener, are you teasing us? Where do we get that thing???
 
#17 · (Edited)
#19 ·
Okay, I'll take 2 :thumbsup:
Is 'PayPal' still okay, or would you like one of my 'flexible' checks ... ;)
 
#20 ·
Yep, John linked it. H4 and T3 use the same plug so it's good to go. I wouldn't even bother trying to build one for the price since this is plug and play and requires no cutting. Only thing I saw in the one I have is that I'd go back and pop the crimp pins/connectors out to solder them. You can also get them on ebay for under $30 with ceramic plugs.
 
#22 ·
So are mine on "Backorder" now :confused:
 
#24 ·
If all the stuff I've ordered that got/is "Backordered" ever all comes in I'm go broke - or have to build a second/third vehicle ... :p
 
#28 ·
It's really a lot simpler than it looks! When I did mine I built a bracket and hid the relays behind the windshield washer tank, ran a fusible link and split it to the positives #30 on the relays and hooked the #87s into their respective lamp feeds after splitting the wire in the loom from the headlight switch and attaching the respective inputs from the switch to either #85 or #86 it doesn't matter which....as long as the other of #85 or #86 goes to ground.

No ugly fuses visible, fusible link hidden along buss bar and wrapped in electrical tape neatly with the other wires, and relays totally hidden behind the washer tank. Nice bright lights with X3 halogen..... cost me a total of $12 buying just the fusible link, wiring, and the 2 relays which were $2.50 apiece. Plus the halogen bulbs from which were I think both for around $50 thru Amazon.

I sure was tired of dim weak lights going on the road at night and having another 60s or early 70s set of wheels flash their ultra brights at me!
 
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#31 ·
Guys, My question is does it make much difference in the brightness of the bulbs? Ive seen the ads, but I want to hear some real world experience. I am very close to doing this upgrade so I can see my way home from the track. LOL!

My bulbs are at least 28 years old so wondering if just putting in new bulbs is all I need.
 
#32 ·
Guys, My question is does it make much difference in the brightness of the bulbs? Ive seen the ads, but I want to hear some real world experience. I am very close to doing this upgrade so I can see my way home from the track. LOL!

My bulbs are at least 28 years old so wondering if just putting in new bulbs is all I need.
As I mentioned in my post above about getting tired of having dim lights while some other oldie cars having triple bright lights flash me at night, the difference in my brightness and intensity is HUGE. At least 3 times brighter. Think of it, halogen bulbs that are rated 3X (3 times) the original bulb....and you are getting 14.2 or more volts at the bulbs cuz of the relays rather than the old 11.5 or so volts when it's routed through the switch.

At night now my 67 machine is as bright as any new BMW with the latest gizmo lights they have.
 
#33 ·
Greg, you have to get a whole new light and not original T3 style although full battery power on them does help. An H4 sealed beam 7" would work I reckon. There are reports of some people heating up their old T3's so they can use the correct looking lens on an H4 as well. A little much I think.
 
#35 ·
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