74 Fuse box- when should fuse Number 5, the top right

[ramairthree]

as you look at it test light up?

It is the 5A fuse.

running or just keys on or off, no test light on either side of fuse.

I am tracking down a couple of things.

oil pressure and temp gauges work, so volt reg. should be good, but fuel gauge is always on E, no matter what I do, remove sending wire from stud, place on bullet proof ground at tank, etc. stays on E.

Also, is there a way to test horn relay/relay slots. I can bench test my horn, but in car nothing.

I was thinking if I had the blades of the horn relay most of the way in, I could probe each with a test light and test horn button on steering wheel.

Thank you for any information.

[Nacho-RT74]

as far I recall.. cluster dimmer lights, powered just with lights on ( parking or headlight position, no matter, since the original source comes from parking lights position )

there is another one on top which protects the RUN circuit into the dash wiring, can't recall which one is on what side, but both on top


fuel gauge:

ground directly the gauge stud with blue wire... if still nothing, feed both gauges stud with 9 volts batt ( JUST FOR A COUPLE of seconds )

if nothing moves, gauge is broken

Horn relay cavities:

they get 3 wires on back by 74 models ( 4 on previous years ). One comes from battery source ( violet wire ), one from horn switch which is a ground ( black wire ) and positive output to horns ( green wire ). Check on back of fuse box which cavity is what wire

[ramairthree]

Thank you.

[ramairthree]

Thank you, that fuse slot has power on the left when headlight / parking lights switch on,
AND
the rheostat turned just right.  Otherwise no power.

I have noticed that with many old rheostat type switches, the no longer work as intended, and either jump switch at full, or not, do not have full dimming and brightening ability like they used to.  Since those lights are so dim even on full compared to modern, not that big an issue.

Cleaned up contacts on the blade connecting the horn wire, new relay, and I have horn function now.  Sadly, the original horn was toast after sitting outside not under cover for years before  I got the car and parts.  Filling it with PB blaster and sitting for ages got some function but no reliable horn, let alone sound right.

I drilled out the rivets, and cleaned it up inside, removed a lot of rust and got really clean, but still no true meep meep sound no matter what.  Definitely toast at this point.  Too bad, will have to get a repo.

[Nacho-RT74]

horns... they have an adjusting screw on back ( 12 points head kind screw ) which needs to be adjusted to be tuned... this regulates the tension on plate what buzzes. They usually can be recovered adjusting that screw.

those light switches are available allmost everywhere, even in Venezuela

[ramairthree]

yeah, I have tried that screw in every position, sadly no luck