Head lights flashing on high beam only. After switching to halogens.

I switched my head lights from the T3 lights years ago. I replaced them with 55 watt halogens. All 4 were changed. This will be for the 1964 Cadillac 75 series limo. The problem is after about 3 minutes on high beam they start to flash on/off. It only happens on high beam. I need the extra  brite lights to see at night being i live in the country. Is there any solution on fixing this problem?

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Is it a flickering or periodic strobing? If flickering check the ground wires just in front of the radiator support where the forward lamp harness comes through the lamp harness. Other than that I have never heard of Halogens making lights flash.  I've pulled in several parts cars that had halogens, and had them on the red SDV I use to own with no problems.

The halogens are overloading the circuit breaker in the headlight switch. Replace the headlight switch. or  put the original style bulbs back in the high beam buckets. For the best results, run a relay system to the headlights.

I have a headlight relay wire harness that is a plug and play, no wire cutting involved.

Its 75.00  and can be seen on my web site www.1963caddyshackk.com  under the "new parts" tab. 

This is a momentery flashing. Then they just go off for abit them come back on. I grounded them to battery& other spots along the front  of body. There is a whole in my dash pad. Was this car setup to have the automatic dimmer sensor?  I took switch out & it has a contact on it like points. The switch was getting hot. I tryed another switch & it did the same thing. Were do i cut the wires for relay? As to your question  on T3 lights they are gone now. This Caddy has been in Upstate Ny for a period of time now. So everything is going bad plus rotting issues.  It will never be a show car. Just trying to keep it around & have fun driving it.  Thanks Paulie.

I did some testing of headlamps and came up with some interesting specs:

- For the older incandescent T3's, the inner high beams ranged from about 3.3 amps to 3.6 amps. They were pretty consistent.
- For the Halogen inners I got a wide range from 2.9 amps up to 4.3 amps. All were obviously brighter than incandescent T3's but the 2.9 amp bulb that looked the newest appeared to be the brightest.

I had similar results with the outer (#2) bulbs with the incandescent T3's vs the Halogens. The Halogen bulb pulled anywhere from 1.0 amp to 2.8 amps on low beam, and 1.8 amps to 3.5 amps on high beam. The T3's were generally in the 1.8 amp on low beam to 3.5 on high beam.

Bottom line, It looks like "some" Halogens are pulling more current than the Incandescent bulbs which makes me wonder o the T3's causing the headlight switch to overload are old ones that have too much resistance due to end of life, or perhaps a different less efficient brand.

I know I have had driver cars with Halogens and did not have any need for special wiring.  This seems to be the due to differences in amp draw from different bulbs.  Paul, If you have a multitester that measured DC amps, I would be curious what your headlamps are pulling?

If someone wants to try a low amp draw Halogen I have them listed at this link: https://www.facebook.com/media/set/?set=a.636729963041382.107374185...

I believe I have the same problem with my '64 headlights. When on high beam the lights will flick on and off a couple times and than go out for about 30-60 seconds. Soon after I purchased the car, five years ago, I replaced all four headlight bulbs with retro headlight bulbs, diamond cut kit from Eckler's. They are H455/60 watt xenon filled bulbs. Are Halogen and xenon filled the same thing? Will the relay system sold by Russ Austin also take care of my problem? I have installed a new headlight switch. a new dimmer switch and installed a separate ground wire from 6" behind one of the headlights to a new clean ground inside the headlight housing area. A couple nights ago the headlights, while on low beams, flicked for the first time.  John Mattingly

John, I do not know any tech info on the new headlights. I do know that the circuit breaker on the headlight switch can be overheated with the high intensity new headlamps.  The relay wire harness will allow you to run the high power demand headlamps, but will not fix a wiring problem.

My first 63 had flickering headlights, and I traced it to a butchered wire harness. 

What you could do to see what is the problem, is to wire in a small bulb at the headlight wire, at the headlight switch.

When the high beams flicker, see if the wired in bulb flickers. If it does, then the circuit breaker is tripping. If the bulb does not flicker, then there is a wiring problem.

I noticed that you installed a ground on one of the headlights?  Both sides are suppose to have a ground wire.

Happy, Happy. I bought the relay kit from Russ Austin and the headlight problem is squared away. The kit is of good quality and the instruction are super simple and complete. Thanks Russ.  John Mattingly

Your welcome.

Paul, the relays directly connect the headlamps to the battery. The stock wiring is the trigger for the relays.  On the setup I sell, you disconnect the headlamps, plug one of the original headlamp connectors to the new wire harness.  

Connect the hot wire to the battery, connect 2 ground wires, and zip tie the new wire harness to the underside of the grill support.

Try sanding the contacts on the circuit breaker on the headlight switch.  If you hear the switch clicking, its the switch.

Also check the wiring at the fuse box. My first 63 Cad did what you are describing. Turns out some yahoo  did a hack job on the main power feed.

I notice some melted wires going on under dash. Located in the harness. That is going to be a big job to sort through that rat nest. I was leaving well enough alone for now. This might be causing head light draw? I also replaced alternator with a 65 amp  with built in regulator.  I'am running two battery's with isolater box to charge second battery. I will take a look  at your harness. Jason wanted me to check head light draw. This car was hacked up before i bought it 15 years ago. Now it is worst with everything shorting out. It was a classy car in it's time & everything worked.

Sounds like you have a lot more problems than just higher current drawing halogen headlamps and need to address the melting wires.   It's easy enough to measure each headlamp if you have a multitester, and halogens that draw the same (or even less) current then the incandescents are available. If you end up needing a complete dash harness I have several nice ones for $75 + s/h. The new repro ones go for $600+.

Should the halogen headlights work correctly in a stock 64 , without any other electrical issues ?
looks like you had them in a prior driver you owned ,with no problem
I also could use more light up front ,on the dark country roads in central Fl at night,have no street lights in some places here



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