electrical Guru

I own a 62 ford thunderbird . The problem I have been having is when I pushed down on the dimmer switch I only get the high beam meaning all four lights our on. When I engage the switch again nothing. This is what I have done so far. I jumped the dimmer switch Switch is good even purchased to new switches upon knowing that I could return them Still the same problem no low beam. I have access to the wiring harness but checking ohms with the red and black wire would be useless since all four lights do come on. I checked the plug inside of the firewall with the back wires still attached to the back of the plug and performed a ohms test on the plug now one side is the hot side which I have power to that. The other two sides show zero ohms on one side and the other shows 0.14 ohms. Would this indicate to someone out there that had the same problem or a electrical indivdual with knowledge of this situation thatsit is a bad plug. Thank You. I no electrical problems can be the worst. Larry

I have a 62 ford thunderbird. I have interior lights also outside headlights that come on. What I dont have is the back brake lights. If I just engage the the parking brakes in the front only nothing but the turn signals will come on through the parking lights in the front and the rear lights will have the lights on also Ill have turn signals in the rear also.THe problem is no front parking lights or rear braking lights will come on when I push down on the brake pedal. I replaced the stop brake light also. Who is my guru out there. Thanks Larry

I own a 62 thunderbird. I have front headlight on but no parking lights. I have parking lights for the back and turn signal for the back. But no brake lights or parking lights to the front. I replaced the brake stoplight but still the same results. Can anyone help with a suggestion. Thanks Larry

i'd try this remove the dimmer switch. Turn on the lights get a test light work out what wire the power is then jump from the power to the other wires and see if you can get the low beam to work. If not plug the dimmer back in then go to the head light unplug the low beam light and see if you are getting power there. If there is no power there may be a loose connector some where. If there is power both the lights might have just blown.

Seems like u have a short circuit somewhere that is between the wires for both hi and low. Take the wires off where they connect on the dimmer switch and do a resistance check between the 2 wires taht go to the lites. If that reads some resistance then u have a short. If it reads open , then no short.
If you have a short there, pull the plug on the fire wall and check again. If the short clears then the short must be in the harness towards the lites.Check the harness with the ohmeter and see.
If you have a short in the harness you may want to replace it because it may have melted at some point and damaged oyher wires in that harness and more problems may be waiting to happen

I believe that your problem is probably in the headlight switch.

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,

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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,

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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.

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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.

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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.