I'm installing relays for the headlights on my '71 Cutlass this weekend and it seems pretty straight-forward.

The green (low beam) and tan (high beam) wires seem pretty small (meaning higher gauge then the 12-gauge hot wire from battery) and I'm wondering ...

What if ...

What if I rewire the headlights with lower gauge wires (probably 12 gauge) from relay to headlights to ground?

Would that provide more current to headlights and make them even brighter? Is it worth the trouble?

 

First question is, where exactly are you putting the relays? The stock wiring is sized to match the circuit breaker in the headlight switch. Unless you are going to some high-current HID lights, there's really no reason to waste the time and money with relays. If you do need the relays, then put then as close to the lights as possible and run heavier gauge wire on the switched legs of the relays. The stock wires would only be providing the control current to the relay coils.

 

Thats a nice upgrade to get brighter lights. Thought I'm not sure replacing those wires with a lower guage will do much. The effect comes mostly from by passing the headlight switch with those relays, which enables you to pull the power directly from the alt.

Anyways, its not a bad idea to use the heavier wire.

 

http://www.madelectrical.com/electri...adlights.shtml

 

I'm willing to bet, unless you are upgrading to a different lighting system you won't find any change in brightness.

 

If you're going to the trouble of installing relays, then why not increase the size of the wire in the circuit from the battery to the relays to the headlights to ground?
It can't hurt, and might help.

BUT, I would agree with Joe, that if you're using regular old 55 watt headlight bulbs, you might not see any improvement.
Relays are usually used to increase the current capacity of the circuit when you're installing components (headlights) that exceed the design capacity of the system.

(And, actually, the HID units do not necessarily draw much more current - their claim to fame is more light for less power. It's the 130 watt halogens that really put a hurt on your wires ).

- Eric

 

Actually a convincing article, Don, though it would be reasonable for each of us to check our own systems before going to the trouble of installing headlight relays with regular headlights - I would imagine that different cars will show different results, and the one that they checked was probably an unusually bad offender.
(As I said above, there is no question that using relays is a good idea when installing more-powerful headlights).

I would point out to the readers that there is no need for any fancy "kit" to do this, just a couple of relays, some wire and wire connectors, some shrink tubing (to make it purty) and a soldering iron and solder, and a half hour to an hour of time.

- Eric

 

What is wrong with the headlights now to need relays? Did you add high wattage bulbs?

Yes, but not enough to make a noticable difference with 60W bulbs. 14 would be an easier-to-work-with compromise.

 

RE: Even though I've replaced the headlights, they are not very bright. I've also noticed that they get considerably brighter if I rev the engine.

RE: I'm adding 2 relays (1 for low and 1 for high beam) and I'm placing them about 1 foot away from the battery (between the battery and the driver side headlights.

Good inputs from all; my understanding is that adding relay will probably help but rewiring the headlights will probably NOT help.

 

RE: Totally agree; in fact, I'm planning on soldering spade connectors to the wires and connecting them directly to the relay. I used the multi-colored pigtail connectors last time and found them to be a little more trouble than I expected.

As always, let me know if I'm heading for trouble by NOT using the pigtail connectors.

 

You're starting to sound like me, Rob .

Naah. ¼" spade terminals should be fine.

The important thing in any automotive electrical repair is to SOLDER everything .

- Eric

 

GLUE LINED heat shrink tube

Silicone ["dielectric" aka "pool"] grease on connections exposed to weather- outside the passenger compartment.

 

Vaseline's usually okay, as well.

- Eric

 

Article sounds reasonable to me, and I like the idea of decreasing the current load on that 40 yr old switch and harness. Might do something to that end next spring, if I can wire it up so it's not visible.

 

Which has NOTHING to do with the switch or wiring and EVERYTHING to do with your alternator or regulator.

If the switch is working correctly, there's no reason to replace it, and if the "40 yr old" part bothers you for some reason, simply replace the switch with a brand new one. If that keeps you awake at night, guess what? The REST of the car is just as old...

But, hey, these vendors make money selling you kits like this. This is like the one-wire alternator bandwagon that negates the GEN light function on the dash. Now the aftermarket will sell you (for an additional cost) a circuit card that senses low voltage and powers the GEN light - JUST LIKE the original three-wire alternator did from the factory...

 

Joe,
I'm curious; how would I know if the problem is my alternator? I replaced the external regulated alternator with an updated internally regulated alternator about 3 years ago.

I only notice the low voltage with my headlights, so where else should I look?

 

You need to measure your alternator's output under load.

Start car, turn on highbeams, blower fan on High, wipers on High, and defogger on High (if you have one).
Set engine speed to about 2,000 RPM (block the pedal, put it on the fast idle cam, whatever works).
Let it run a minute or two.
Measure voltage from the battery ground to the big terminal on the back of the alternator, then to the horn relay lug, then to the hot headlight wire (don't unplug it - you'll change the reading).
You should have about 14v everywhere, certainly no less than 13.5.
If you've got about 14 at the alternator, but a lot less somewhere else, you've got a bad connection between those two places.
If voltage looks good everywhere but the headlights, then you've got an argument for installing relays, but you should check the continuity of your headlight switch before you do that.

- Eric

 

What is your idle rpm set to? The lights will dim a bit on most older cars at idle, so relays will not correct this.

 

Even my 97 caddy's lights will dim slightly at idle, esp with the AC on. One volt can make a difference. This is even noted in the caddy's owner's manual as being normal.

 

If the headlights are dim at idle due to the alternator output dropping at idle, then changing the wiring won't help. Check the voltage at the headlight connector as compared to at the alternator lug at idle and reved up. If they're close, then wiring isn't causing any problems.
Depending on what alternator you have, it may simply be undersize, or possibly failing. Note that I'm a fan of adding relays, but make sure you're fixing the right problem.

 

[QUOTE=joe_padavano;479098]Which has NOTHING to do with the switch or wiring and EVERYTHING to do with your alternator or regulator.



If the switch is working correctly, there's no reason to replace it, and if the "40 yr old" part bothers you for some reason, simply replace the switch with a brand new one. If that keeps you awake at night, guess what? The REST of the car is just as old...

Never said I wanted to replace the switch. I was referring to potential voltage drop over a long as opposed to short run in addition to possible corrosion of old connections. Similar in theory to the hot start relay that cured my problem. I think there is a good chance this could increase the brightness of a bulb. And I'm not talking about alternator output or engine RPM.

 

Well you can run a temporary jumper and test that theory without going through the expense and trouble of the relays. You will probably find that your issue is not with your wiring.

 

Funny, because you said this:

It's your money and time, do what you want, but there were no relays installed or required when the car was new. Extra parts are simply more potential failure modes.

The hot start relay is another example of an unnecessary part. The hilarious thing about it is that even with this extra Ford-style relay, all current for the starter STILL goes through the contacts in the original starter relay. A far better solution is to just fix any corroded terminals or replace the contacts inside the original starter solenoid. I'm cheap. I don't like to buy parts that I don't need.

 

+1 on that.

(Though I will admit I will be stooping to install a generic $4 lighting relay in my Chevelle's purple starter wire to cure a low-voltage condition at the solenoid that I'm just too lazy to fix. It's probably because of the amalgamation of wires I ran from the battery to the dashboard and back, when I was a teenager, so that I could run an ammeter, but I'm not quite up to buying a roll of 6ga wire to do that one right just now.)

- Eric

 

I know the current still goes through the contacts in the starter. The relay (I would never use a Ford style solenoid) bypasses the ignition switch,NSS and all the wiring under the dash. The far better solution may have been to replace the dash harness, but I'm cheap and lazy. What's funny about decreasing current through an old switch.. Am I the only person who's seen terminals on a switch that look overheated and burned?

 

<.....................reaches for the popcorn

 

Which means you're in good company.

No, but the obvious response is that a new headlight switch is about $12 at your local auto parts store, and easier to install than a pair of relays.

Also, for the motivated, the old headlight switch can be disassembled and cleaned.

- Eric

 

Sure, at which point I throw it away and replace it. Sorry, but bandaiding a bad switch or corroded terminals with a relay is like slathering silicone sealer over rust at the base of the windshield. New cars use relays to cut down on total copper used and to allow computer control Ffor things like twilight sentinel functions. Personally I've more trouble with those relays than the simple direct wiring in my older vehicles. The most reliable part is the one that isn't there.

 

[QUOTE=joe_padavano;480110]Sure, at which point I throw it away and replace it. Sorry, but bandaiding a bad switch or corroded terminals with a relay is like slathering silicone sealer over rust at the base of the windshield.

Of course I would replace a component that was overheated, melted or excessively corroded. I'm talking about possibly avoiding that in the future by cutting the load on the circuit. I'm not trying to "band-aid" anything. You keep making assumptions and drawing conclusions that make me look like a total hack. I'm only a partial hack!

 

I'm not making assumptions (and contrary to popular belief, I'm not trying to bust your chops - much), just going by what you've written. I pointed out that the circuit worked fine for 40 years without relays. You brought up the burned contacts. I pointed out that replacing the damaged switch fixes the problem without relays. You're now talking about preventing damage (to a switch that worked fine with no relays for 40 years).

Look, I get it, you want to install relays. Knock yourself out. I'm just saying that it really isn't needed here and it will introduce more potential failure points with additional connections and wiring than the OEM design.

There IS one place where I do advocate installing relays where the factory did not use them, and that's on the mid-1980s B-body cars with power seats. Prior to 1986, GM used relays on the power seat motors. Starting with the 86 full size wagons, GM deleted the relays to save a few pennies, running full motor current through the switches in the doors. Unfortunately, they did not upgrade the contacts in the switches and replacement switches are simply not available. My 86 wagon is like this and I'm constantly disassembling the switch to file the contacts. This is a case where the switch contacts were NOT designed to carry full current of the circuit but GM used them that way. This is NOT the same as the headlight switch in the original thread.

 

A way to prevent burning and pitting would be to make sure the contacts are clean, tight, and coated with a little dielectic grease to prevent corrosion.
A dremel tool with a little wire brush will shine up those contacts like a new penny.
It sounds a lot harder than it is. Come join me in Rob's Skule of Terminal Repair!
https://classicoldsmobile.com/forums/...tml#post312739
If it looks as bad like my resistor connector, then replacement will be required.
https://classicoldsmobile.com/forums/...tml#post322115
Simple rule - If it will not polish up, replace it.
Once you do a few of these, it goes fast.

Make sure the load is not overloaded (like oversized bulbs), too.

 

No arguments, and I understand the impulse, but, in the particular case of the headlight switch:

• These switches are not known to inevitably go bad - a few do, probably because of abuse (miswiring by previous owners, etc.).
• In the event that one does go bad, they are easily replaced, by original units from junkyards, by easily available NOS units, or by brand-new units from the auto parts store.

In light of this, is it really worth the trouble?

- Eric