I have a 72 Challenger and after about 15-20 minutes of night time driving my headlights will go out. Keep in mind my dash, tail lights, brake lights all continue to work. It almost seems like once my car is running good and up to temp then bam... the headlights go out, stay off for a few seconds and come back on. Continually getting worse by going off and staying off for longer periods of time then come back on. Why would they work right away but go off after just a short period of time? Please help

 

This is one of about three things

First, the headlights are not fused before the power gets TO the light switch. On or in the light switch is an automatic BREAKER

1--If you have installed heavier wattage headlights, they may be drawing more current than original and the breaker may be marginally weak

2--The breaker may be marginally weak

3--The harness connector at the light switch, or even bad connections right in the switch (contacts going bad, example) may be causing HEAT which warms up the breaker and causes it to trip

This is a classic example of headlight system problems

If you wander around the www there are several ways to add headlight relays which do several things:

They are getting the heavy headlight power out under the hood, so power no longer has to go through the bulkhead connector

Relays relieve the pressure on the headlight switch, the dimmer switch, and other wiring.

You can hide these, example, under the battery box