My front parking / marker lights go out when my headlights are switched on. “Why?”, is a common question. You may expect both should be on at the same time. Apparently it was a thing in the 60s, at least for GM, to have the headlight switch work this way on several models.
If you want your front parking / marker lights to remain on when the switch is pulled to headlights, there are many forum threads and posts about this. Some suggest adding a jumper wire to the headlight switch from Light Blue (headlights) to the Purple (front parking lights). You may have seen an image depicting this in many places on the web. While this may allow the parking / marker light to remain on during headlight operation, it will also cause the headlights to be on in the parking / marker light switch position, meaning you will not have parking / marker light only operation. It also can cause damage if you do not use the correct wire gauge per required amperage and make certain you have a good connection between the two, so just don’t risk it.
If you want to keep front parking / marker lights only operation and also have the parking / marker lights illuminate during headlight operation, I suggest a safer and neater way is to wire in a simple relay as shown in the image below.
