headlights are not working . ground issue ? 1973 dart slant 6
At this point you are either down to a ground issue or the headlights are bad. To check that, pull out either lamp a little so you can access the connector, with the headlamp still connected. With the HL switch on, clip your meter ground to the battery neg. to start with and probe the connector. 1 of 2 will have power at a time and the other is ground, so this can be confusing.
With HL power OFF you can first identify the ground terminal by probing the connector for continuity
Here is a headlight connector, BK is ground here
Anyhow, one of the two "non black" should have power depending on whether the dimmer is in hi or low. So with the lamp connected, and lights powered on, if you show power on say, lo beams, and the ground is good, it is gonna be the lamp.
You can use your meter and "ohm" the lamp. All three pins show continuity to each other on a good lamp
At this point you are either down to a ground issue or the headlights are bad. To check that, pull out either lamp a little so you can access the connector, with the headlamp still connected. With the HL switch on, clip your meter ground to the battery neg. to start with and probe the connector. 1 of 2 will have power at a time and the other is ground, so this can be confusing.
With HL power OFF you can first identify the ground terminal by probing the connector for continuity
Here is a headlight connector, BK is ground here
Anyhow, one of the two "non black" should have power depending on whether the dimmer is in hi or low. So with the lamp connected, and lights powered on, if you show power on say, lo beams, and the ground is good, it is gonna be the lamp.
You can use your meter and "ohm" the lamp. All three pins show continuity to each other on a good lamp