The Stovebolt Site Forums The Shop Area The Electrical Bay Dim Headlights

The headlights on my 49 are real dim. I've converted it to 12v. The headlights are so dim you hardly see anything. I checked for a bad ground. I even ran a ground from the headlights directly to the ground on the battery. I also tried new lamps and a new switch. Nothing seems to help. Hope somebody here can get me going in the right direction. Thanks

Did you install a relay between the switch and the bulbs to send full power to the bulbs?

What size wire is used? Could it be too small?
What is the voltage measured across the bulb?

I rewired the whole truck using an EZ harness. I didn't put in anything extra. Do I need to add an extra relay?

I ued the wire supplied in an EZ wiring harness. I'll have to get out there later and check to see if I'm gettine a full 12 volts to the lamps. Thanks

A headlight relay is not a bad idea but not usually necessary, and not a cure for other troubles that may already exist.
See what voltages are and if low at the light start checking further and further back to find the trouble. Don't forget the ground path is just as important as the wiring.

Do you have an original headlight switch? If so you might want to check the resistance on the bi-metallic thermo overload switch that is part headlight switch. I have found that the contacts are prone to corrosion over time and consequently limit the voltage going to your headlights.

Check the voltage drop across the dimmer switch. It should be less than 1/10 volt.
Jerry

Just replaced the headlights in my '55 2nd. The old ones were real yellow and dim. Got a set of halogen sealed beams off ebay, and what a difference. Twice as bright, just sayin.....

I was using Halogen 9004 in my headlights. They had also gotten very dim. The reflectors had tarnished and turned dark.

I bought an HID kit on Amazon and installed it yesterday.

WOW, it's now like daylight in front of my truck.

Be carefull when installing new modern bright headlight bulbs to your old truck wiring. The new lights can draw more amperage than the old lights and overload the headlight switch and wiring.

To correct this problem just add a Headlight Relay.

Mike B

I'm using a modern aftermarket harness with 12 volts and a 30 amp circuit breaker. No problems here.
But if you are still on an old harness...take caution.

The OEM dimmer switch will be a potential problem, as well as the bimetal circuit breaker in the headlight switch, even with good wiring. Adding a relay or two is good common sense anytime a set of high-output halogen lights are installed.
Jerry