quad headlight change out
 

Has anyone performed the upgrade of the mid 80s truck quad headlights to the lights that take bulbs in the back of them? I am working on that very task and have come up against an interesting thing. With the top lights changed out, the lower lights (High Beams) come on dim, when the low beams are selected (turned on). It appears that there may be a lack of ground circuit or not enough resistance in the low beams to keep the high beams from being illuminated. Can anyone let me know if you experienced this and what did you do to solve it? I have not put in a pair of relays and wiring harnesses, but that is what I will work on tomorrow.

Re: quad headlight change out
 

Maybe new lights are drawing more amps. Might be wise to do a relay setup? After all they are running all that current through the H/L switch.

Re: quad headlight change out
 

I found the problem after I had a chance to sleep on it. They guy that built the adapters for the factory headlight plugs to go to the 9007 bulbs, got the wires crossed, so the headlights were searching for a ground through the high beams. It took a little time to change the plug terminals around, but they now work right. The bulbs that I am putting are 55/65 watt, so they should not pull too much amperage.

I am still considering a wiring harness and then upgrade to a high wattage bulb set, but that is in the future. The price for a good one is really high, so I am looking for one that will work, but won't cost me a fortune.

Re: quad headlight change out
 

You will find that the low beams go off when you power the high beams
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Re: quad headlight change out
 

Are you talking factory or the upgraded harness?

My 86 stock would have all four on
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Re: quad headlight change out
 

Right now, with the factory harness, the headlights have all four on with the high beams selected. The headlights that are on top (Low beams) are a dual filament bulb and they have both the high and low capability. The plugs are also three pronged for the low and only two pronged for the high beams.

The issue that I was having is that the adapter from the factory headlight plug to the aftermarket plug was wired wrong and the wires were crossed, not giving a solid ground circuit for the headlights, thus it was feeding back through the high beams to get the ground. While doing this, the high beam headlights would power up with a dull glow and not give full voltage to the low beams at the same time. I changed the pins around in the plugs and the problem is solved.

Re: quad headlight change out
 

I used two relays one per side and two diodes to prevent back feeding granted I have a hid setup but it does the same thing for all types. The high beams are stock harness and the low beams on relays. If your interested I will see If I can make a diagram for you
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Re: quad headlight change out
 

I am always interested in diagrams for improvement. I happen to have a set of DDM HIDs on my shop shelves, just haven't found a place for them.

Re: quad headlight change out
 

You don't need diodes when using HID or any relay harness. There is a very easy way to prevent back feeding and only requires a couple wire splices.
Your dimmer switch has 3 wires going to it.
They are.
B+
Hi beam
Low beam
Cut the low beam wire and splice it into the B+
Leave the other 2 connected.
Now when you pull the headlight switch it powers the low beams without going through the dimmer.
All the dimmer switch does is switch the high beams. Low beams stay on controlled by headlight switch.
No diodes required

Re: quad headlight change out
 

I use the relays for the hids so both of them ignite reliably. They draw quite a bit on initial arc then power down. I will see about doing that on my other trucks. This still allows quad lights correct?
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Re: quad headlight change out
 

yup. Hi/Low on/off
I should mention that I spliced mine right at the dimmer. (steering column)
As for Relays,
I believe that anytime you upgrade your headlights whether Halogen, HID or whatever you should awalys
install relays. You can buy a pre made harness or pick up a couple relays and do the wiring yourself.
For those who don't know, the headlight circut on our trucks suffers from high resistance and excessive voltage drop
when used with anything except the stock sealed beams. The power has to travel through the headlight switch, Dimmer switch
fuse box many connections with very small gauge wire. By using a relay with the proper connections and wire size you bypass
the troublesome connections and power straight from the battery to the lights.
As INSIDIOUS mentioned, HIDs require an inital surge that the factory wiring has trouble providing and Halogen draw alot
of power all the time they are operating.
Even with the factory sealed beams you would see a noticeable difference in brightness just upgrading the wiring and using relays.
And the older the truck the poorer the wiring and bigger the improvement.

Re: quad headlight change out
 

Yah I found out the hardway on my old Buick before I was apart of any forums that the stock headlight switch has an internal breaker that will kill your lights. It happened when I was driving down a dark road with no street lamps for miles with my brights on. My h4 conversion drew so much that the lights triggered the breaker and shutoff my lights except the running lights. That was scary! Ever since then I've always done relays and never had issues. I'm sure it's safer this way not to mentioning sure all new cars are like this now
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