Headlight questions

[Rengo]

I am working on my 1975 Plymouth duster and have an issue. Sometimes at night I will lose lights, idk if it is a short or bad lamp bulbs, when it rains they work great... Bad ground?? I need input and want to know how much new lights cost/ where to get them. Parts store didn't have them :/

 

[TrailBeast]

If they work intermittently youd be wasting your money buying new ones for that reason alone.
Could be bad connections at the lights, hi/lo switch or even the headlight switch.
OR, a ground like you said.
Give em the wiggle test.
Turn them on and start wiggling connections.

 

[67Dart273]

I agree the headlights are the last thing I'd suspect, especially if BOTH are quitting

Do BOTH lamps quit?

High beam? Low beam? BOTH?

Pay attention!! Check the high beams, does the dash indicator STAY ON when the lamps are out??

If so, the headlight switch and dimmer switch are OK, and the problem is either in the bulkhead connector or out in the engine bay

Check the ground for the headlight harness out by the lamps, and check the lamp connectors for corrosion/ looseness.

Some of your top suspects:

Bad ground out at the headlights

Bad/ corroded headlight connectors. (Usually affects only one light!!!)

Bad connections in the bulkhead connector (Usually affects only either high, or low beams)

Bad dimmer switch -- check your high beam indicator!!!!

Bad headlight switch -- affects high or low, has a built in breaker that can get weak, the connector may be loose/ corroded, or the switch going bad. check your high beam indicator!!!

Failed "welded splice" in the under dash harness. It happens!!! This splice is taped up under the dash in the harness, a few inches from the black ammeter wire connection, as branches off to the fuse panel hot buss, the ignition switch, and the headlight switch, 'n maybe coupl' o' other things.

 

[wjajr]

First suspect is foot operated hi-low beam switch. These become compromised over repeated contact with wet or snow covered footwear. They are inexpensive to replace.

 

[Rengo]

I replaced the headlights because I had an extra set, I replaced the switch and they work now. The old switch was very rusty, I believe there is a leak dripping down my dash onto the switch.. As my car is a POS.

 

[Oklacarcollecto]

Glad you got it. I have ran in to this issue with the dimmer switch more than once. I used to own a car that I carried a new one in the glove box because once a year it would take a crap, damn import trash. I finally found a real NOS one and never had to replace it again.