Thread: electrical Guru

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Unplug both low beam headlight bulbs.

Take a test light and see if you have any power to the bulb socket when it's on "low beam".

If you have power, then you have a poor ground, (maybe even a burnt out bulb(s).

If you don't have power at the socket plug, start tracing it back to the headlight and dimmer switch until you find the open.

Headlight switches have circuit breakers inside that can fail.

Don't overlook the plug at the firewall were both main harnesses plug together,

Originally Posted by John Palmer

Unplug both low beam headlight bulbs.

Take a test light and see if you have any power to the bulb socket when it's on "low beam".

If you have power, then you have a poor ground, (maybe even a burnt out bulb(s).

If you don't have power at the socket plug, start tracing it back to the headlight and dimmer switch until you find the open.

Headlight switches have circuit breakers inside that can fail.

Don't overlook the plug at the firewall were both main harnesses plug together,

If he has all 4 lights on he can't have a burnt out bulb, bad ground, no open circuit, and 62's didn't have circuit breakers in the headlight switch.

On a four light system two of the lights are single element high beam headlights (usually the inner pair?), while the other two are dual element, hi/low beam lamps. You could have burned out the low beam elements of the two dual filament bulbs, likely losing one and not realizing it, then losing the second one taking out your low beams. I would first check the bulbs with jumpers from the battery and be dead sure that all filaments are good. The low beam terminal is the horizontal one by itself, and the high beam and ground run vertical on the sides - looking at the back of the headlight if you have the low beam on the bottom, the ground is on the right.

Originally Posted by rspears

On a four light system two of the lights are single element high beam headlights (usually the inner pair?), while the other two are dual element, hi/low beam lamps. You could have burned out the low beam elements of the two dual filament bulbs, likely losing one and not realizing it, then losing the second one taking out your low beams. I would first check the bulbs with jumpers from the battery and be dead sure that all filaments are good. The low beam terminal is the horizontal one by itself, and the high beam and ground run vertical on the sides - looking at the back of the headlight if you have the low beam on the bottom, the ground is on the right.

Exactly, could not have said it any better.

But.........I have spent enough time working under the dash on 1960-70's era T-Birds, to feel sorry for anyone needing to work in the limited space under the dash on those cars. It's usually turns out to be something simple with electrical problems, so eliminate all of the easy to check things first.

Good luck.