Grounding issue?

[86SilverFox]

1986 LX 5speed

Had an issue for awhile but don’t drive much. Everything works as it should and drives fine. When I turn on the headlights the seat belt buzzer stays constant, both turn indicators and bright light indicator lights up, tach and fuel gauge stop working. Instrument cluster lights do not work but fuse is fine. I and not knowledgeable in electrics at all.

Any suggestions?

 

[AeroCoupe]

Get this and a DVM.

Color Wiring Diagrams

https://www.ebay.com/itm/324526616152?mkcid=1&mkrid=711-53200-19255-0&siteid=0&campid=5335821607&customid=&toolid=10001&mkevt=1

 

[General karthief]

Grounds would be my first thought. Without some background on this car I would say check the ground on the back of the drivers side head to firewall,
Oh, got any LED bulbs swapped ?

 

[nickyb]

Suggestions don't turn on the headlights?
But seriously pull the headlight switch ,check wires,connectors.

 

[86SilverFox]

I have had no luck locating what is causing the issue. All ground I can find seem to be good. Located this today. The 2nd wire coming out of #2 spot on the instrument cluster goes no where. The black and green wire is intact but the black is not? Car was originally a v6 but now is v8 and has a ford performance fuel injection harness.