On my 1996 Mustang GT, when I turn on my headlights, my dashboard lights go out. Is that a fuse, ground or some other issue?

" dim headlights "? None of your lights should be 'dim'. You have 4 lights.

Side Lights.
Daytime Running Lights (DRL)
Low Beam Headlights.
High Beam Headlights.

Here are the fuses, check fuse 5 and D although they covers more items than lights. Your best bet is to find a good local auto-electrician.

1994-1998 Ford Mustang Fuse Box Diagram

https://knigaproavto.ru > ... > Ford > Mustang

17 Oct 2019 - Fuse Panel Diagram Ford Mustang Mk.4 engine: 3.8L, 4.6L, 4.9L, 5.0L and 5.8L (1994, 1995, 1996, 1997, 1998)

More here

https://www.google.com/search?q=1995+ford+mustang+gt+v8+low+beam+headlight+not+working

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engine runs perfect?
head lights full power bright>? 2 questions, and shows battery is at 12.6vdc rested and 13.3 to 15vdc running, (is it>?_)
ill pretend yes......
blown fuse. what else could cause so many things, to lose DC power.
>?
a fuse can be good, bad or intermittent , even corroded,
a tech would scratch head and pick the easiest fault to fix.
my guess, is
dashboard doesnt work means the guages , and idiot lamps are dead but the park lamps there (dimmable) do work.
so what fuse is that.? i say to self.....
I open the FSM. and look at the power cluster feed.
what do i see.?
posted over 100 times here.
http://www.jeep4x4center.com/knowledge-base/index.htm?utm_source=cj#service

i look in instruments page. (aka. cluster)
tells you how it works
then i jump wiring page 8w-40-2
i see what, Fuse 10. is it good? and fuse 17.
fuse 10 is key on,, and fuse 17, is hot full time.

thats it, if the cluster is dead, only fuses can kill it 100% dead
or it losts its main ground, which is unlikely but voltmeter proves
in 1min flat. (G201)


i picked right, the cluster dead, is the most simple
if Headlights are dead, its most simple (not in Canada with DRL)

bingo?

check power suply relay is the must powerfull relay in the car and the fuses

Your problem may be a lost ground. A lost or loose ground wire will make you pull your hair .

turn the knob for the headlights all the way to the left and then the right. it's also a dimmer for the dash lights.

Fuse? Is your ignition fuse the same as some interior lights? Does your dash lights turn on?

are the lines like /// or wavy?? could be the car had factory fog lights /// or could be headlight defroster (didn't know it was available on a stang)

Check headlight lamps... then follow the wiring from the bulb connections back and make sure you're getting a good solid ground connection. It may have a loose, broken, severed grounding wire.. it's usually attached to the car body at some location not far from the headlights.

its in the power distribution box under hood test all of them with a test light

Probably either a bad ground (broken wire, rust) or a bad headlight switch. The brake light circuit goes from the stop switch (Located up above the brake pedal) through the headlight switch, through the light bulbs to ground. The tail light circuit goes through the headlight switch, through the bulbs and to ground. The only things that are in common are the headlight switch (Is this the switch you replaced?) and ground.
Not much, but hope this helps.
Have a super day!
Ron