removed head unit

[SilverEclipse96]

Is it normal for the headlights and interior lights to not work if the head unit is disconnected?

 

[JuGs]

No they run on different circuts. You might of knocked a ground loose somewhere or blew a fuse.

 

[Turbo1976]

That, or the person who wired up the radio may have tapped into the wire for the lights...was the radio installed with a wire harness or were the wires just spliced together?

 

[Foz]

There is an illumination wire in the radio harness, so that your switches and knobs light up when you turn the radio on.

If that wire accidently catches ground, it can blow out the fuse for the lights. Hence no lights...

Sounds like you got a quick easy fix, clean up the wires behind radio and change fuse.