I thought I had a blown fuse because it blew before. However, I installed a new fuse and still my interior instrument (dash) lights will not come on. I took the fuse block off and ran a meter on the terminals behind the interior lamp fuse location and they were not getting power.
If I'm not mistaking, I think the fuse gets it's power from the light switch. Please correct me if I'm wrong as I am guessing and have no schematics.
Is this a common problem or do you think my light switch went bad? My headlights still turn on, just don't get power to the fuse for the interior lamps. And yes, I checked the dimmer on the switch and moved it both ways, so they are not dimmed. haha
Please advise what you suggest I do next.
__________________
Thanks,
Jeremy
1965 Mustang Fastback 2+2
289 V8
C4 Automatic
Semper Fi USMC 1999-2004
Last edited by jatepper; 04-06-2009 at 10:56 PM.
Reason: Clarification I'm talking about dash lights.
Hello. The power goes to the headlight switch by means of a couple of wires, but, the one that goes through the fuse box goes from the fuse box to the headlight switch, not the other way around. If the fuse has no power to it, that problem is upstream from the headlight switch, so, no, it isn't the headlight switch that's doing that to the fuse.
Here are the wiring diagrams for your car. http://thecareandfeedingofponies.blo...-diagrams.html
Last edited by Veronica; 04-06-2009 at 11:23 PM.
Reason: added diagrams
Hello. The power goes to the headlight switch by means of a couple of wires, but, the one that goes through the fuse box goes from the fuse box to the headlight switch, not the other way around. If the fuse has no power to it, that problem is upstream from the headlight switch, so, no, it isn't the headlight switch that's doing that to the fuse.
Hmmmm. Well, the headlight switch still works because my lights work, so where is the headlight switch getting power from then?
Where do you suggest I start at in regard to troubleshooting?
Hi again. There is a black wire with a yellow stripe that comes off of the hot side of the starter solenoid. It supplies power to the fuse box. But, before it gets to the fuse box, there is a black wire with an orange stripe that splits off of it and goes straight to the headlight switch. That's why the headlights work whether the key is on or off. They draw power straight from the hot side of the starter solenoid. There is a blue wire with a red stripe that goes straight from the fuse box to another spot on the headlight switch. That's the fused power to the courtesy lights. If the other lights work, and the other stuff that runs through the fuse box also works, then the problem would pretty much have to be that slot in the fuse box itself. There are some companies that make fuse box repair kits, none of which I can recall off the top of my head, , but, I'm sure that someone here will, or you could google it and see what you come up with. Hope that helps.
Hi again. There is a black wire with a yellow stripe that comes off of the hot side of the starter solenoid. It supplies power to the fuse box. But, before it gets to the fuse box, there is a black wire with an orange stripe that splits off of it and goes straight to the headlight switch. That's why the headlights work whether the key is on or off. They draw power straight from the hot side of the starter solenoid. There is a blue wire with a red stripe that goes straight from the fuse box to another spot on the headlight switch. That's the fused power to the courtesy lights. If the other lights work, and the other stuff that runs through the fuse box also works, then the problem would pretty much have to be that slot in the fuse box itself. There are some companies that make fuse box repair kits, none of which I can recall off the top of my head, , but, I'm sure that someone here will, or you could google it and see what you come up with. Hope that helps.
I removed the fuse box from the fender wall and actually checked the wires feeding to the back side. None of the wires had power (without ignition on, with ignition on, and with accessory on), so I have a hard time thinking it is the fuse box. It's gotta be something that supplies the power to the fuse box.
Hi again. That's why I said " and the other stuff that runs through the fuse box works" Your problem just got real simple. The black wire with the yellow stripe that comes from the hot side of the starter solenoid and supplies power to the fuse box has a problem somewhere berween the fuse box and the place that the blue wire with the red stripe splits off from it, since the headlights work. I would start with the connection of that wire to the fuse box and work my way back to the blue wire to find the break. It's probably corrosion at the connection to the fuse box, though. Isn't this fun?
Hi again. That's why I said " and the other stuff that runs through the fuse box works" Your problem just got real simple. The black wire with the yellow stripe that comes from the hot side of the starter solenoid and supplies power to the fuse box has a problem somewhere berween the fuse box and the place that the blue wire with the red stripe splits off from it, since the headlights work. I would start with the connection of that wire to the fuse box and work my way back to the blue wire to find the break. It's probably corrosion at the connection to the fuse box, though. Isn't this fun?
All of the other fuses DO get power, just no the instrument light fuse. You still think this is the problem? The lights worked before and I blew a fuse. When I went to change the fuse, I forgot to disconnect the negative battery terminal and installed the fuse. Obviously the fuse sparked a little and the instrument lights didnt work, so I thought I obviously blew the fuse when I went to install it. Turns out the fuse was good, so this is where this whole dilemma began. Now I have no power to this one terminal.
Hi again. If the other fuses do get power, then the problem can't possibly be upstream from where the black wire with the yellow stripe hits the back of the fuse box. That eliminates a wiring problem on the battery side of the fuse box. No problem is possible downstream from the fuse box that would prevent that one fuse from getting power, because the power is flowing in the wrong direction for that to happen. That eliminates a wiring problem on the dash side of the fuse box. Something unique to that one slot in the fuse box is all that remains. Either the wire that sends power to that one slot from the main power feed, the connection of that wire to the clip in the fuse box, or, the clip itself is what's causing the problem that you have described.
Hi again. If the other fuses do get power, then the problem can't possibly be upstream from where the black wire with the yellow stripe hits the back of the fuse box. That eliminates a wiring problem on the battery side of the fuse box. No problem is possible downstream from the fuse box that would prevent that one fuse from getting power, because the power is flowing in the wrong direction for that to happen. That eliminates a wiring problem on the dash side of the fuse box. Something unique to that one slot in the fuse box is all that remains. Either the wire that sends power to that one slot from the main power feed, the connection of that wire to the clip in the fuse box, or, the clip itself is what's causing the problem that you have described.
10-4. I concur. I just can't seem to trace that wire where it's coming from. It's a mess under the dash. Please advise if you can. Thanks.
Hi again. Here are a couple of pictures to show you what you are dealing with without having that pesky Mustang wrapped around it.. The first is of the fuse box and all wiring that brings power to the fuse box. As you can see, " all wiring that brings power to the fuse box" consists of a grand total of one wire. In the second picture, the red arrow indicates the wire coming from the hot side of the starter solenoid, the yellow arrow indicates the wire taking power to the ignition switch, the blue arrow indicates the wire taking power to the headlight switch, and the pink arrow indicates the wire taking constant power to the fuse box. Everything in the fuse box gets power from the ignition switch except for, that's right, you guessed it, the courtesy lights, the emergency flashers and the cigarette lighter. The third picture shows you the back of the fuse box. The blue arrow indicates the contact for the courtesy lights. The red arrow indicates the contact for the emergency flashers. You can see how, if something had gone stupid on you with that contact, your courtesy lights and emergency flashers would stop working. It sounds to me like your problem would pretty much have to be somewhere between that little black junction where the wires split off to the headlight switch and ignition switch and the contact on the back of the fuse box.
Try replacing the headlight switch. I had the same problem today and replaced it. Dash lights started working as soon as I did. The fuse box problem was exactly the same for me but was resolved by the new light switch. I dont know much about wiring but this worked for me.
Try replacing the headlight switch. I had the same problem today and replaced it. Dash lights started working as soon as I did. The fuse box problem was exactly the same for me but was resolved by the new light switch. I dont know much about wiring but this worked for me.
It was indeed the head lamp switch. The headlamp switch has a blue/red wire going to the fuse box which supplies power to the instrument lights via the blue/red wire leaving the fuse box. Took out the trusty test light and was not getting power from the headlight switch (turned on) and the blue/red wire leaving to the fuse box.
Hi again. Cool. Glad you finally figured that one out. Ultimately, that's how all electrical issues are solved. Get out the test light or volt meter, dig in and go find out where the break is.
No power to interior lamp fuse 
The power goes to the headlight switch by means of a couple of wires, but, the one that goes through the fuse box goes from the fuse box to the headlight switch, not the other way around. If the fuse has no power to it, that problem is upstream from the headlight switch, so, no, it isn't the headlight switch that's doing that to the fuse. 
, but, I'm sure that someone here will, or you could google it and see what you come up with. Hope that helps. 
The first is of the fuse box and all wiring that brings power to the fuse box. As you can see, " all wiring that brings power to the fuse box" consists of a grand total of one wire. In the second picture, the red arrow indicates the wire coming from the hot side of the starter solenoid, the yellow arrow indicates the wire taking power to the ignition switch, the blue arrow indicates the wire taking power to the headlight switch, and the pink arrow indicates the wire taking constant power to the fuse box. Everything in the fuse box gets power from the ignition switch except for, that's right, you guessed it, the courtesy lights, the emergency flashers and the cigarette lighter. The third picture shows you the back of the fuse box. The blue arrow indicates the contact for the courtesy lights. The red arrow indicates the contact for the emergency flashers. You can see how, if something had gone stupid on you with that contact, your courtesy lights and emergency flashers would stop working. It sounds to me like your problem would pretty much have to be somewhere between that little black junction where the wires split off to the headlight switch and ignition switch and the contact on the back of the fuse box. 
