Link to brighten your headlights

[oldschool90]

Well, I was going to post a howto for headlights, but I found this instead: Headlight relay wiring. I decided instead to just post a link to this website so I didnt have to spend hours typing and drawing diagrams. So this topic is basically a Q&A topic for people who need help doing this. Did it myself on our ford van and let me tell you, what a bigdifference it makes!! Our battery was getting 14+ volts, but the headlights were only getting 10 volts through its 18 gauge wire harness. Now they are getting 13.8 volts. Oics coming soon!

[datzenmike]

Absolutely. Many of our older Datsuns were made before the advent of halogen headlamps and had very small gauge wiring which was fine for the old tungsten filaments. I had a new '76 B-210 and swapped halogen lamps and soon after while flying down the side road at night had the singular experience of the lights going out from a blown fuse. Nasty experience. So yes the newer lamps draw more power through thinner wires and fuses blow. You could go to larger fuses but this does not fix the underlying problem. Separate relays for high and low with fuses and using 10 or 12 gauge wire will reduce the voltage drop at the bulbs. Even better would be individual relays and wire to each headlight for the ultimate voltage to the bulbs.

 

Don't forget that current flow is equal in any part of a closed circuit so if you increase the current flow into the bulbs you must also increase the wire size to ground as well. Think of it as building a 4 lane highway to your work but having a mud path home.

[ggzilla]

Here's a Datsun-centric writeup: http://datsun1200.com/modules/mediawiki/index.php?title=Headlight_Wiring#Relay

 

You can either

* buy a harness ready made (only $129 USD "Painless Wiring Headlight Harness with relays")

or

* roll your own, $5 using Nissan relay and parts from Pull-a-Part, and a bit of work

 

 

Common Nissan relay

[paradoxx]

interesting info here!

[Papi Chulo]

I've been meaning to do this to my car for awhile now and this thread was a nice reminder. Rewired them tonight

 

12.7v batt

10.2v at the light before

12.5v at light after 12ga and relay

[Unclejesse88]

on the 510, I just unplugged the red/yellow wire at the fuse box, and instead ran it to the control side of a relay. The other control wire goes to ground. Fused power off the starter terminal feeds the input of the power side of the relay. The output of the relay connects to the red/yellow wire going into the fuse box. Using terminals I bought at vintage connections and a relay base, I was able to make this simple four wire harness plug and play, no cutting of factory wiring. Sure, headlamp power still runs through the fuse box. What I gain is power from the battery straight to the headlamp fuses, instead of going all the way into the headlamp switch and back. This also removes 90% of the current flow through the headlamp switch, making it last longer because now the switch only controls a relay at 30mA.

[ggzilla]

Sound much eaiser. Just modify it a little bit by putting in inline fuse where you attach it to the starter.

 

Without it, there is a safety flaw -- an unfused wire going into the passenger compartment, a potential fire hazard. The Fusible Link won't protect it. But an inline fuse like this will.

[Unclejesse88]

GGzilla, if you are talking to me, I did say fused power from the starter terminal. But to make it clear, I did install an inline fuse, with a 20 amp fuse to feed the two stock 10 amp fuses in the fuse box

[ggzilla]

Sounds good. I like your method.