Electrical issue..flashing headlight

GONDO79 · Jul 30, 2009

Any good suggestions or suspicions why my headlight flash?
I checked for a bad ground last night up front and rear and nothing. I cleaned up the ground conection points just in case and wire wheeled the screws. The lights almost flash as if it were attached to a flasher(like an emergency or signal flasher)

After removing the old flasher I still had the problem! It was replaced wit a new one and again no luck. I checked the hi/low switch on the floor and its working fine. Battery voltage is good too!

So Im not sure if its the actual light pull switch on the dash or a hidden short somewhere.

TT670 · Jul 30, 2009

Change the headlight switch! The headlight switch carrys the entire load and is the most common cause of flashing lights. If you really want to do yourself a favor, put the headlights on a relay. You gain 2 things, first obviously is the load being removed from the switch but a side benefit is since the headlight load is removed from the switch, theres more power to the tail lights and they become significantly brighter as do the Headlights because theyve got direct battery voltage. For the $$$ its a very worthwhile modification. Mines wired so I get both low and high beam operating when my high beams are on. With modern H4 bulbs it lights up the night pretty good for an old car.

jcode68 · Jul 30, 2009

Is it both headlights or just one? If just one, then try switching the bulbs (left to right, right to left) to see if the problem follows the bulb or stays on the same side. If it follows the bulb, replace the bulb. If it stays on the same side, could still be a bad ground or short in the wire somewhere. If both bulbs, then as posted above, probably the switch. Not sure it would be the switch though if it is only happening on one bulb.

Wart · Jul 30, 2009

IIRC, the headlight switch has an internal breaker for the headlights. On other Fords with a failed breaker I've seen the lights go on for a while, then off for a while, then on for a while ... Or it could be a high resistance short causing the breaker to trip.

OTOH I've also seen Pulsing lights referred to as flashing lights. For some reason people notice the pulsing in the head lights and not so much in all the other lights.

I've seen pulsing lights from mis-matched alternators / regulators (one mechanical the other solid state), old regulators running on the over volt solenoid, and bad regulator grounds/ bad grounds period (battery to chassis to engine to alternator) , that is IIRC.

LTL EVIL · Jul 30, 2009

Flashing Lights

Dang, it sucks chasing shorts...not the 2legged kind!
Sound like it's the light switch...x2 on the relay. Anybody here have a how to wire up the relay?

GONDO79 · Jul 31, 2009

TT670 said:
Change the headlight switch! The headlight switch carrys the entire load and is the most common cause of flashing lights. If you really want to do yourself a favor, put the headlights on a relay. You gain 2 things, first obviously is the load being removed from the switch but a side benefit is since the headlight load is removed from the switch, theres more power to the tail lights and they become significantly brighter as do the Headlights because theyve got direct battery voltage. For the $$$ its a very worthwhile modification. Mines wired so I get both low and high beam operating when my high beams are on. With modern H4 bulbs it lights up the night pretty good for an old car.

thanks

GONDO79 · Jul 31, 2009

Is there a site/link to where I can read or see how to wire it up??

Rusty67 · Jul 31, 2009

Use the search button.

tx65coupe · Aug 1, 2009

I have my headlights on relays, its a great modification like was already stated.

Here is a link describing it so you can make your own.

Brighter Headlights

I just bought this one. Its really a very simple install and is basically plug and play.

RJM Injection Tech Headlight Harness

I had the problem of my headlights cutting off when the high beams were on. It has to do with the fact that the headlight switch is not rated for the amps that Halogen and increased wattage bulbs pull.

Mine was doing this with regular Halogen replacement sealed beams.

I now have Sylvania Xtravisions with the relays and its a great setup. It puts out plenty of light. The XV 6024 bulbs still look like stock sealed beam but are the same wattage as the newer capsule bulbs.

68er · Aug 30, 2009

my bronco had the same problem. chased that demon till my hair came out. the solution made me feel like a real dumbass - just swap the voltage regulator. cheap and easy. its jumping from charge to discharge real fast causing current to spike/dip. $6.95 at autozone.

Electrical issue..flashing headlight

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