Author Topic: Wiring all four headlights to come on when hi beams are on  (Read 5057 times)

Offline pholliday1

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Wiring all four headlights to come on when hi beams are on
« on: January 29, 2013, 02:04:28 PM »
Any drawbacks? And whats the best way to do it? More light has to be better right?
VETERAN AND LIFETIME NRA MEMBER. WHAT DO YOU STAND FOR?
1991 V3500 CREWCAB SRW 454TBI GMC
1991 v3500 crewcab SRW 454tbi 480le 6" lift
1990 V3500 crewcab Dana 60 FF 14b 5:38 ratio 40 inch 11" lift
1989 v3500 crewcab 454TBI 5" lift

Offline 84burb

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Re: Wiring all four headlights to come on when hi beams are on
« Reply #1 on: January 29, 2013, 03:44:47 PM »
All 4 should be lit when on Hi beam. If they aren't, which ones are not lit?
I just realized, I've become one of those Ol' Geezers I didn't need to listen to when I was young.
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Offline pholliday1

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Re: Wiring all four headlights to come on when hi beams are on
« Reply #2 on: January 29, 2013, 04:14:04 PM »
Mine have one set for low and one set for hi so maybe they have been wrong for awhile? If i understand you correctly on a stock oem setup all bulbs are lit on hi?
VETERAN AND LIFETIME NRA MEMBER. WHAT DO YOU STAND FOR?
1991 V3500 CREWCAB SRW 454TBI GMC
1991 v3500 crewcab SRW 454tbi 480le 6" lift
1990 V3500 crewcab Dana 60 FF 14b 5:38 ratio 40 inch 11" lift
1989 v3500 crewcab 454TBI 5" lift

Online bd

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Re: Wiring all four headlights to come on when hi beams are on
« Reply #3 on: January 29, 2013, 05:40:45 PM »
Your '90 has discrete high and low beam, single filament lamps.  All four illuminated at once isn't DOT approved for your vehicle, so check around in your area to determine how local law enforcement deals with it.  Keep in mind that City, County, and State authorities may have different policies.

Now to your question, more light is always a plus!  If you plan on switching to higher wattage bulbs (illegal for on highway use), you'll want to power them through relays and 14-gauge wire.  Even with stock wattage bulbs, powering through relays maybe the prudent approach to keep from overburdening the headlamp switch if you choose to power all at once.

To remain highway legal you might consider Sylvania Silverstar Ultra bulbs.  But, higher wattage bulbs and high performance bulbs that burn hotter have a shorter service life than bulbs approved by DOT for highway use.
« Last Edit: January 29, 2013, 08:45:18 PM by bd »
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
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Offline pholliday1

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Re: Wiring all four headlights to come on when hi beams are on
« Reply #4 on: January 29, 2013, 09:09:57 PM »
Thanks BD! Current setup has been wired using relays and I used existing wires as control voltage. So do I use a third relay to control both on high beam?
VETERAN AND LIFETIME NRA MEMBER. WHAT DO YOU STAND FOR?
1991 V3500 CREWCAB SRW 454TBI GMC
1991 v3500 crewcab SRW 454tbi 480le 6" lift
1990 V3500 crewcab Dana 60 FF 14b 5:38 ratio 40 inch 11" lift
1989 v3500 crewcab 454TBI 5" lift

Online bd

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Re: Wiring all four headlights to come on when hi beams are on
« Reply #5 on: January 29, 2013, 09:14:30 PM »
How many relays do you have now?

How did you wire them?

Do you want manual control over the 'quad' illumination, so you can defeat it at will?
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline pholliday1

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Re: Wiring all four headlights to come on when hi beams are on
« Reply #6 on: January 29, 2013, 09:23:55 PM »
I have 2 relays direct voltage from battery (fused) and control voltage from oem high and low beam not really a priority to defeat quad illumination ? What do you think?
VETERAN AND LIFETIME NRA MEMBER. WHAT DO YOU STAND FOR?
1991 V3500 CREWCAB SRW 454TBI GMC
1991 v3500 crewcab SRW 454tbi 480le 6" lift
1990 V3500 crewcab Dana 60 FF 14b 5:38 ratio 40 inch 11" lift
1989 v3500 crewcab 454TBI 5" lift

Online bd

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Re: Wiring all four headlights to come on when hi beams are on
« Reply #7 on: January 29, 2013, 09:52:40 PM »
I think better when viewing diagrams on paper, but if I duplicate you.... 

As long as you are using at least 14-gauge supply wires individually fused to the low and high relays, (and assuming Bosch-style relay numbering with your battery supplies connected to the '30' terminals) run a redundant control circuit from the high beam relay '87' terminal to the the low beam relay control terminal (85 or 86, depending on how you wired it) through a 1N4004 diode, with the cathode pointing toward the low beam relay.  That way, high beam will energize the low beam, but low beam cannot energize the high beam.  This method will be cheaper and more elegant than additional relays.

Incidentally, on the low beam circuit, I would seriously consider switching the fuse over to an auto-reset circuit breaker.  You can drive without high beams, but no low beams at night might get dicey.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline pholliday1

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Re: Wiring all four headlights to come on when hi beams are on
« Reply #8 on: January 30, 2013, 07:40:59 AM »
Aaah the diode... the electrical equivalent of a one way check valve,good idea! We must be thinking along the same lines as you described my existing setup to the letter. However if I choose to wire the setup with the ability to "defeat" the quad setup as you suggested, maybe the third relay is the way to go?
VETERAN AND LIFETIME NRA MEMBER. WHAT DO YOU STAND FOR?
1991 V3500 CREWCAB SRW 454TBI GMC
1991 v3500 crewcab SRW 454tbi 480le 6" lift
1990 V3500 crewcab Dana 60 FF 14b 5:38 ratio 40 inch 11" lift
1989 v3500 crewcab 454TBI 5" lift

Online bd

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Re: Wiring all four headlights to come on when hi beams are on
« Reply #9 on: January 30, 2013, 09:37:33 AM »
In that case you could install a simple switch (or relay) in series with the diode, between the existing high and low relays.  There may be other ways to configure it, as well, that would require reinventing the wheel.  Since you already have infrastructure in place, why not take advantage of it?
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline pholliday1

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Re: Wiring all four headlights to come on when hi beams are on
« Reply #10 on: January 30, 2013, 11:53:15 AM »
Understood..... Thanks again for the guidance.
VETERAN AND LIFETIME NRA MEMBER. WHAT DO YOU STAND FOR?
1991 V3500 CREWCAB SRW 454TBI GMC
1991 v3500 crewcab SRW 454tbi 480le 6" lift
1990 V3500 crewcab Dana 60 FF 14b 5:38 ratio 40 inch 11" lift
1989 v3500 crewcab 454TBI 5" lift