So ive ben working on my dash lghts for a bit now.

I got back at them today and I find I dont have hardly any lights.
All I have are signal lights and headlights.

No dash , radio , dome , tail , sidemarker lights.

79 F-250

Ive changed the headlight switch.
Checked fuses.
All fuses have power on both ends of them with the exception of one which doesnt have power in or out of it.

That fuse is a small one on the top right and of fuse box.

Anyone got any ideas where to start?

 

Couple questions.
By no radio, do you mean no radio, or no radio lights? Factory or aftermarket radio?
Is the "small fuse" the one a 3A stubby fuse?

Factory radio fuse is on the left, just after (below) the fuel tank selector.

Because of this, my guess is actually the black/green wire coming from the ignition switch. Either there is a problem with the wire, or the switch is broken internally.

Hopefully someone else will chime in to either verify this or provide other insight

 

All of the lighting you mentioned are all on the same circuit, I believe tail lights asweel. I would not think it to be a wire short because that most likey would only affect one of the lights not all. Recheck fuses, sometimes corrosion can prevent the flow of current. I'm no pro, but if you poke around at it, your bound to figure something out, That's what I always do.

 

Oh... Make sure grounds are in conjunction.

 

That 3 amp fuse is for the PRNDL lamp, cluster, and panel illumination. http://fordification.net/tech/images...aster_1of9.jpg Time to break out the test light and figure out where you're losing power.

Doesn't explain the dome, tail, and sidemarker lights, though.

 

The dash light fuse is the top left, and since that seems to be included in your list of fuses that have power on both sides, that eliminates the headlight switch and dash illumination fuses as a possible culprit. The dash light circuit is a BLUE with RED stripe wire that is distributed throughout the dash. You'll need to troubleshoot where power is dropping out between the fuse panel and the bulbs.

The tail lights and side marker lights are fed by a BROWN wire out of the headlight switch and are separate from the dash light circuit. The radio is a separate circuit, and it sounds like you've verified the fuse for this is good too.

If you are confident in your measurements thus far, then my first guess would be that a previous owner has had some fun with the wiring behind your dashboard, and you'll need to dive deep to understand how.

 

Ive had everthing right out of the dash.
It was wide open and I couldnt see anything to bad looking but there was a few jonts but they looked clean and well done.

Dome light doesnt work either.

In fact hardly anything works.

Im not to bad at wiring I guess i just have to keep looking.

The signal lights work but the green arrows on the dash dont.

The radio works but the light in it doesnt.

Heater fan works but the light doesnt.

 

Ok, let's take a step back. Did this just happen, or have these items never worked?

I am stumped because most of those are on the one circuit (the fuse you said didn't have any power) but some of the other stuff is on a different circuit.

My current line of thinking is that the entire bank is dead.
Do you have dual tanks? If not, you might not know that the dual tanks and emissions circuits are dead as well.

 

He said the only fuse that doesn't have power is on the top right, which should be blank. That made it sound like everything in and out of the fuse box is good, unless I'm misinterpreting something. Also note that all the items in question are separate circuits. A '79 has many more fuses than earlier years. Dash illumination is its own fuse, dome light is its own fuse (courtesy lights), radio is its own fuse. Tail lights and side markers do not go through the fuse box. The only thing that's common to all of that (except the radio) is the headlight switch, which is upstream, and could be the problem. The fact that his headlights work mean power is at least getting to the headlight switch, but maybe something is wrong with the headlight switch and it's not throwing power to everything it should. However, if he has power on both sides of the dash illumination fuse (which I am to assume based on his description), then that means that part of the headlight switch is working, since the dash illumination fuse is sourced off the headlight switch.

To the OP's claim: if all the wiring behind the dash is good, the headlight switch is good, and all the fuses are good, then something is not adding up. Either you have made an assumption (and something is not actually good), there is a missing piece to the story, or there is a typographical error in your description of the problem.

 

This is why it is good to have several sets of eyes reading this.

Like you, I would have thought the light switch, but he said it is good. This is why I am confused. The way I see it, there's only two ways all these things have something in common: 1) the headlight switch, or 2) power to the fuse panel. Even that doesn't completely add up.

 

Agreed. More advice to the OP: please specify the label of the fuse location that has no power. Since your profile says Canada, maybe what you're working with is different than what I'm looking at. My other advice would be to actually verify power coming out of the various circuits of the headlight switch to prove it out.

 

I could try another headlight switch I guess.

Every fuse except the short one in the top right hand corner has power both coming into it and going out of it.

Further examanation reveals some bad looking tailight wiring but I can fix that.
Right at the back where someone added a trailer plug.

Doesnt explain any of the in cab stuff.

 

Can you make out the label of this fuse? As I said before, my wiring diagram claims this spot should be blank, but I don't know if a Canadian-built truck would be different.

Instead of swapping in yet another headlight switch, check for power coming out of the one you have (I mentioned this before). With the headlight **** pulled out to either of the two stops and turned all the way counter-clockwise such that it clicks into place, you should see power on all three of these wires coming out: BROWN, BLUE with a RED stripe, and BLACK with a BLUE stripe.

 

So I checked switch again.
No pwer on the blue wire with the red stripe.

There is power in 3 places.

The 2 green wires have powee.

@ blue with black stripe have power.

1 orange with black stripe has power.

Checked all fuses again and they all have power except that small top right hand one.
It has no power on either side of it.

 

Did you do this with the headlight **** pulled out and rotated all the way counterclockwise as I described previously? If YES, the switch is defective. If NO, try again.

I'm assuming you mean GREEN with a YELLOW stripe, in which case this is good. This is hot-at-all-times power INTO the switch for the dome light.

Do you mean BLACK with a BLUE stripe? I'm assuming this shows up with the **** rotated all the way counterclockwise as I described previously? If YES, then that's good, and you need to figure out why power isn't making it from here to the dome light (make sure the bulb isn't burnt out). If NO, then explain the conditions of the test. Are you saying that the dome light does not come on with the headlight switch, OR does not come on with the doors, OR both? Not coming on with the doors is a separate issue. Please clarify.

I assume you meant BLACK with an ORANGE stripe; that's good, it means you have power going into the switch (you wouldn't be getting power out of the switch at all if you didn't).

Okay, thank you for the clarification and the helpful picture. I didn't realize that the shop manual has the map rotated from how it sits in the truck. You don't have any power to your dash illumination fuse. That's because the BLUE with RED stripe wire coming out of your headlight switch is not getting power. This is why your dash lights are out. That means you need to go back to my first comment and described how you checked for power coming out of the BLUE with RED stripe wire with regards to the position of the headlight switch ****.

To summarize, you need to:

1) Figure out why the headlight switch isn't getting power to the BLUE with RED stripe wire. Either the switch is bad, or you have the dimmer all the way down (my first comment).

2) Clarify when your dome light is NOT coming on. If it's not coming on with the doors, that's separate from the headlight switch. If it's not coming on with the headlight switch, then you need to trace out why power isn't making it from the headlight switch out to the dome light (after making sure the bulb is good).

3) Check for power out of the BROWN wire of the headlight switch.

4) Figure out why power isn't making it from the radio fuse to your radio. UNLESS, you're talking about the radio ILLUMINATION and not the radio itself. If your radio is working, but it just doesn't light up, then that problem is grouped with your dash light problem because the radio illumination is fed from the same BLUE with RED stripe wire.