Lamp out with high beam on

[V6&V8SHO]

First here are the basics

New headlight switch
New multifunction switch
New headlight harnesses
New alternator
Autolamp wires and connector in excellent condition


Problem-

When I turn on my highbeams I get a lamp out light and my left side headlight is not as bright as the right side.

Lights currently in are Sylvania Silverstars, IE the $36.00 ones that are 9007


I replaced with regular 9007 bulbs and the situation still persists.

What is causing my lampout light and decreased output from the left side when the highbeams are on?

Thank you

 

[Slo-Sho]

First thing I would do is get out my trusty digital multimeter and probe the highbeam + wire at the headlamp plug and probe the battery + post and measure the line drop.

 

[SHOZ123]

You are getting less current draw than normal because the lamp is dim. That is causing the lamp out light to be on.

I would suspect the ground or a bad plug. Excellent candidate for a headlight harness.