Hello

There is a very large class of people that own 65/66 Mustangs that, as far as I can tell, anyway, have been, for the most part, ignored entirely. They don't really want that 100 pt. show car that is so nice and was soooo expensive that they're afraid to drive it, they also don't want to make their car capable of achieving warp factor three. They just want this car that they dearly love to be able to cruise around smoothly and reliably, without having it dump them out on the side of the road or have it start making weird noises or belching out big clouds of funky-smelling smoke. And I think, truth be told, that this is by far the largest class of Mustang owners. They take their car to some technician when what they actually need is a mechanic, and this, frequently, does not work out very well at all for the owner. They don't want to re-engineer the entire car, they just want someone to fix what broke. These are the people that I am trying help out with this blog. Some problems require a little bit of back and forth, as in, "Try this." "I tried that and it didn't change anything."
" Oh. well, you probably need to try that." " I tried that and it helped, but it still isn't quite right." "Now you need to try this...." If you go to http://www.allfordmustangs.com/ and then go to the classics forums, you will be able to do that with a pretty hefty gathering of some very knowledgeable people that also happen to be very friendly. None of that ridiculous one-upmanship, no flaming or abuse, none of that stuff. Just good, solid advice from people that know what they are talking about.

Friday, February 25, 2011

Mustang Fuse Box 1965 1966

Many questions seem to arise concerning this seemingly simple component, such as "Where is the main power feed?' or "How do I replace this with the more modern blade type fuses?"  First, there is no 'main power feed'. Here is how the wiring is on the 65/66 Mustang fuse box.
In the bottom left corner of the picture there is a contact with a black wire with a yellow stripe attached to it. There is a black/yellow wire coming from the hot side of the starter solenoid, the same terminal that the positive battery cable is attached to, which comes through the firewall, splits into three wires, one black/yellow, one black/orange and one yellow. The black/yellow wire on the fuse box is the black/yellow wire coming from the starter solenoid. This is constant power, whether the key is on, off or in the accessory position. The power is always on, thus, the term, 'Constant Power'. (insert smiley face.) You will notice that this contact has two round thingies on it. If you flip the fuse box over, you will see that one of those round thingies is the hot side of the fuse for the cigarette lighter/emergency flasher circuit, and the other is the hot side of a circuit called 'Dome'. A 65/66 Mustang does not have a dome light. This is the interior courtesy lighting which comes on when you open either door. On the other end of the Dome fuse is a green/yellow wire. This green/yellow wire goes out to the driver's side door jamb switch.  On the other end of the cigarette lighter circuit is a blue/white wire. This goes out to the lighter, and splits off before it gets to the lighter and also goes to the emergency flashers, if your car has the emergency flashers. Not all 65 model Mustangs had emergency flashers.

On the middle fuse you will have two blue/red wires. One of them brings power directly from the headlight switch and the other goes to the instrument cluster back-lights. Those are the ones that come on when the headlights come on, not an alternator/generator warning light, or the oil pressure warning light.

In the top right corner, there is a black/green wire. This brings power from the ignition switch when the key is in the on or accessory position. Again, the wire is attached to a contact plate with the two round thingies. The one on the top is the hot side of the accessory fuse. There should be a wire hanging out of the front of the fuse box on that circuit which supplies keyed power to whatever accessories are plugged into that wire on the other end. The other round thingy, marked by the brown/green arrow, is the hot side of the heater fuse. There is a brown wire coming out of the other end of this fuse. If you have three speed heater fan, this wire goes out to the fan motor. If you have a two-speed, center-position/off heater fan, this wire goes to the fan switch. The fuse box of a 64 1/2 is a little different in a couple of ways. I'll address that one in another post.

So, as you see, power goes to the fuse box from three different places, the starter solenoid, the ignition switch, and, the headlight switch, and the systems that get power from one are pretty much completely isolated from all of the others. There is a little more involved in replacing this with a blade type fuse box than just removing this fuse box and sticking the new one in. The new one needs to either have a provision for isolated independent power feeds for different circuits, or, it needs to be more than one fuse box. 

54 comments:

cyndel said...

Super information. I wanted to cut my old block out and replace it with a new style one. Your write up made it a snap to use a generic 5 circuit block from the auto parts store and wire it right up correctly.

Thanks

Joe

Veronica said...

I'm happy to hear that you found the write-up to be useful. There are a lot of advantages to the more modern style of fuse box.

sammy,pop your eye out said...

I just rewired my 65 mustang with. Brand new wiring oem kit, though I thought the fuse box was a newer sale box. It's not . What's your recommendations to install a newer box? This blog is awesome! Thanks, God bless, Mike Diaz Nor- Cal.

Veronica said...

The easiest way would be to have one fuse box with constant power, which has the black/yellow wire feeding it constant power and the emergency flashers/ cigarette lighter on one circuit, and the courtesy lights on another. You would still have a couple of slots left over on this, so you could also route the wire that supplies power to the headlight dimmer switch through the box on one slot and the taillights through another. Take a second small fuse box for the keyed power stuff and have the dark green/black wire supplying the power to the box and have the keyed power stuff. This way you would also have slots for things like a phone charger, power amps for the sound system, etc.. Whatever you wanted to run in your car. The blue/red wire for the instrument lights you would want to just put an inline fuse and skip the actual box, since this is a dedicated circuit that is simply power in/power out for the dash lights.

It's actually quite simple and not at all expensive. Just make sure that you use fuses of the same amp load as the originals. If you have something that seems to keep blowing fuses unless you go with a higher amp fuse, you have a problem somewhere and the fix is not simply use a heavier fuse.You have a short somewhere, or excessive resistance for some reason, something. The fix is to fix it.

Joe F said...

Troubleshooting why the back up lights in my (dad's actually) 65 mustang do not work. Been reading Chiltons and 65 Ford Shop manuel, but your diagram is great. Thanks. On fuse box, no power to 2.5 interior light fuse, and one half of cig lighter. Also trying to understand how starter neutral switch is involved. I'm a novice. Any tips from my ramble appreciated.

Joe F said...

troubleshooting back up lights on 65 Mustang. So far, found out no power to 2.5 fuse in box for inst. lights and 14 fuse on one side of cig lighter. I think power to backup lights come from starter neutral switch.

Joe F said...

65 backuplights are down. All other fuses accesories working now. So...back to how to check 65 backup lights. Found 4 red/black wires going into Starter Neutral switch, which I believe is the power that goes back to red/black lights for two back up plus power & ground for Starter Neutral switch. Yes?

Veronica said...

Hi again. The switch doesn't have a main power-in and fround, like some switches. It's just a wire taking power through the switch. If the switch isn't in the right position, the power stops there because it doesn't have anywhere to go. When the switch is in the right position, the power just passes through, on the red/blue wire to the starter solenoid,and, on the black/red wire to the reverse lights.

LeLu said...

This was extremely helpful! I used your description to re-wire in a newer style blade fuse box which was cut out of another car. Knowing what all of the wires go to was crucial in making sure I wired it up to the new box properly. I made sure to include a link to this post the entry. This is the second time your blog has come to the rescue in my restoration!

Mike said...

Very useful information Veronica. I also used this diagram to wire in a new blade type fuse box. I only used one box as I found some splitters that you can connect to the 1/4QC connections that turn it from one QC into 2 1/4 QC plugs. Its basically a single female to 2 male plugs so then I just had to solder on the 1/4 connectors and plug them in. Thanks again.

Lee Walls said...

Will this help me on my 68? The speedometer is the only gauge working. I also dont have in dash lights. The turn signal and bright light indicators do work.

Lee Walls said...

Will this apply to my 68? The only gauge that works is the speedometer. The turn signal and bright light indicators do work.

Veronica said...

The dash lights not working could be a blown fuse, but, they could also not be working because of a faulty headlight switch. And, yes, it is very common for a headlight switch to fail in a way that has the headlights working and the instrument lights not working.

The speedo is a purely mechanical assembly and doesn't have any wiring in it at all except for the light. If the other gauges don't work, you should read through this. http://thecareandfeedingofponies.blogspot.com/2008/03/gauges-dont-work.html The gauges on the 68s work in the way as the 65/66 cars. One thing that is different on your car is that to remove the instrument cluster you have to pull the heater controls out far enough to be able to get your hand in there to disconnect the speedo cable. Hope that helps.

0a7db2a4-2c78-11e4-837e-df3027495c46 said...

Hi Veronica,

The dash lights in my 66 are not working, I replaced the headlight switch and they are still on the fritz. All other lights work fine, and the fuse is new. What would your next step be to diagnose/fix this issue? (News flash: I know very little about wiring!)

Thank you,
John

Veronica said...

Hi, John. Assuming that you have also replaced the bulbs, the first thing that I would check is the dash ground wire. On the back of the instrument cluster there is an instrument cluster voltage regulator. This is a rectangular thingy which has two black wires with green stripes plugged into the back of it. There should also be a black wire attached to the instrument cluster by the same screw that holds the instrument cluster voltage regulator on. The other end of that wire should be attached to the bracing behind the dash with a screw.

0a7db2a4-2c78-11e4-837e-df3027495c46 said...

Hi Veronica, Thanks for your reply. I checked and cleaned the dash ground, still no lights. I then checked behind the fuse box, looked good. So I just started unplugging and replugging anything with a blue/red wire... Lo and behold, let there be dash lights. Hope this positive trend continues. Thanks again for all you do for vintage Mustang owners. John

Riccardo said...

Hello Veronica

I have just bought a 66 mustang K code convertible. I cannot for the life of me find the fuse box. I have spent ages digging around under the dash and no luck. I hope you can help me with a few questions.

1. Where is the fuse box? ( i do not from what I can gather have emergency flashers)
2. While digging around I found a black wire with a male ending - and then another black wire with a female ending (they push into each other) they were not connected - I connected them but so far I have not seen anything happen.
3. I bought a new lighter socket as I need power for my navi and the lighter was not working. When I disconnected the old one I found it was not connected at all and I cannot find any loose wires - where should I try getting the power from?
4. On the passenger side there is a little "closet" under the dash with a door - what is that for?
5. Finally in 4th gear the gear seems to slip up and start rattling - it does not pop out of gear - just seems to not stay seated all the way - any ideas on that?

thanks so much

Riccardo - Italy

Veronica said...

Ciao, Riccardo. That sounds like a fun car to have. I love the K codes, and the convertibles. A K code convertible would be just about as good as it gets for me.

1) The fuse box is attached to the car behind the driver's side of the dash, right above the driver's side kick panel. The bottom edge of the fuse box is just a little bit above the top edge of the kick panel.

2) Where, exactly, are those two black wires? If they are part of the main underdash harness behind the instrument cluster, and are actually black with a red stripe, those are part of the back-up lights wiring.

3) All 66 Mustangs came with emergency flashers, and, the cigarette lighter wire is part of that wiring. The emergency flasher switch is supposed to be inside the glove box, attached to the top of the glove box liner. There should also be a blue wire with a white stripe that has a female connector with a 90 degree bend in it hanging around somewhere kind of near the ignition switch which plugs into the back of the lighter.

4)That little closet is the passenger side fresh air vent. With that door open, there should be fresh air coming out of it when you are moving down the road.

5) On that thing going on with your transmission, it would be difficult to do anything other than just make a wild guess, and my guess be about as reliable as what you could get from a ouija board. With that being said, something that effects only one gear would just about have to be inside the transmission.

Riccardo said...

HI Veronica

thanks so much for the quick reply.

So I definitely do not have the emergency flashers - nothing in the glove box and unless there is a secret switch somewhere I have not found them. Also I do not have reverse lights (unless the brake lights just come on - there are no white lights at the back.

The mystery back wires were behind the dash just above the lighter - the male seemed to head off over the steering column and the female seemed to up into the darkness :-) - the horn does not work so I am not sure if that is a clue.

While I have your kind attention - I have a radio - original which lights up when you turn it on but it makes no sound - mainly I think as I cannot find a speaker :-) - where would it be if I had one.

I will have to dig some more under the dash - not an easy task :-)

If you get to italy give me a shout I will take you for a spin - she runs like a dream :-)

Veronica said...

The emergency flashers were standard equipment on the 66 Mustang, as were the back-up lights. Your car definitely left the factory with both of those things. It sounds like someone has replaced that rear valence panel with one that doesn't have the holes for the back-up lights. Who knows why people do some of the strange things that they do. That black wire that you mentioned sounds a lot like wire that supplies power to the radio. The speaker is (was) in the middle of the top of the dash, underneath that center grille thing that is attached to the dash by two screws.

My husband and I spent about a month in Italy a couple of years ago and had a wonderful time. We might spend a couple of weeks in Bormio this summer.

Riccardo said...

Hi Veronica

Glad you enjoyed italy. Your comment about the back up lights worried me so I did some research. On this site

http://www.mustang-s.com/years/1966/1966_mustang.htm

I seem to understand that on the 66 Mustang the back up lights were an option that cost $10 - but they were not an option on the 1966 K code GT like mine - or have I misread the site?

thanks

Veronica said...

In the 1965 model year back up lights were an option that cost $10.40, but, in the 1966 model year, the back up lights were standard equipment. I have a rather large stack of original publications from Ford to document this. I am not familiar with that particular site, but, if they said that the back up lights were optional in the 66 model year, they are mistaken. If you send me an email that I can reply to, I would be happy to scan some of these publications and send them to you, just so you can see for yourself, rather than have one of those 'He said, she said' things going on. Your car did indeed come from the factory with back up lights.

Riccardo said...

thanks Veronica - my email is skirabbit at gmail dot com

I will try and do more research as well - the car was/is - in mint condition so I am a bit disturbed that they would have changed something. :-)

Veronica said...

I just sent you a couple of scanned pages. I wouldn't be too concerned with the fact that somebody changed something on the car. You have a car that is half a century old. Or, another way to look at it would be that your cars age right now is 25X the original manufacturers warranty period. If you call the average life expectancy of a person 70 years, and you encounter someone that is 1750 years old, he's probably had a bit of work done on him along the way.

jacob pickett said...

I seem to have a pretty common problem looking at some of these posts,hope I don't bore you too much.I have a 1966 mustang 6 cylinder and the dash lites have stopped working,everything else works fine.I replaced all the bulbs,the headlite switch and the fuse.Now everytime I turn the lites on it blows the fuse.Helppp

jacob pickett said...

I have a 1966 mustang 6 cylinder and the dash lites have stopped working.I have replaced all the bulbs,headlite switch,and the fuse.Now everytime I turn the lites on the fuse blows.Helpppp

jacob pickett said...

I have a 1966 mustang 6 cylinder and the dash lites have stopped working.I have replaced the headlite switch,bulbs,and fuse.Now everytime I turn on the lites it blows the fuse.Helppp

Veronica said...

These old cars are never boring. It seems that they can always find interesting new ways to befuddle their owners. My first guess would be that one of the wires feeding the dash lights is shorting out on something. I would pull the instrument cluster out and have a look at the condition of all of the dash light wiring.

Trent Timson said...

On my 66, the courtesy lights won't turn off with the car on and doors shut. Sometimes if I jiggle the ignition, I can get them to turn off, but then I lose the turn signals. Something is draining my battery too. It's brand new but is dead every time I go to start it. Thanks for any advice!
Trent

Trent Timson said...

Hi Veronica, sorry if this posts 3 times. My courtesy lights on my 66 won't turn off. Light switch is not turned to the left. Sometimes, if I jiggle my ignition, they will go off, but then I lose my turn signals. Also, something is draining my battery. Appreciate any help. Trent

Veronica said...

I have it set up here in such a way that I have to see and ok any comments that people might try to leave. The vast majority of people are good, decent people that just want a little help trying to figure out what's wrong with their car, but, occasionally, up pops 'That Guy' that either wants to post spam, or something tacky, or just say something ignorant which has absolutely nothing to do with an old Mustang to try and anger people, and get a reaction from them. I don't see how any of that facilitates people repairing their old Mustangs, so, I just delete them. The downside of that policy is that it might be a little while before I see that a comment has been made, and, the person making the comment has no way of knowing that their comment will be posted as soon as I get back from Krogers, so they might think that there was some sort of computer glitch and repost something. I happens on a fairly regular basis.

As far as your electrical weirdness goes, you obviously have a short of some sort, possibly in one of the door jamb switches, maybe in the headlight switch itself, or, maybe, the two wires that go into one of the door jamb switches are shorting themselves out on each other. There are several things that could cause the problems you are having. I would start with the easy stuff first. Unplug one of the door jamb switches and see if the lights go out. If no, do the other one. If the lights are still on, pull the dome light fuse. If that makes them go out, you'll need to pull the instrument cluster out and have a look back there. I suspect that the problem will end up being the door jamb switch wiring because that stuff goes across a whole bunch of sharp sheet metal edges back behind the kick panels, but, there really isn't any way to narrow it down without going through the motions. There is no substitute for actually having a look inside. Let me knowwhat you find out.

Trent Timson said...

I gottcha. Sorry. Ok, what I discovered is.... I dont think the light that stays on is really the courtesy light. I got the passenger courtesy light working just fine by putting the bulb in better. It's much larger than the light on the drivers side (the one that stays on). This light doesn't even fit in that ring properly. I bet it's an instrument light that came out and somebody just put it in that courtesy light ring.
Is there a dash light that stays on all the time, with the key on? If so, we're good. I just need to put that back where it belongs, AND, try and find where the actual courtesy light socket is hiding! If this really is the courtesy light, then I still have a problem. Thank you for helping me!

Veronica said...

The only light behind the instrument cluster that come on whenever the key was turned on would be the high beam indicator light, and then only if the high beams where on. If the wire attached to that questionable bulb is green with a black stripe, try stepping on the dimmer switch and see if it goes out. If that is not what you have going on, it would help out a bunch if you could determine the color(s) of the wire going to that socket.

Trent Timson said...

I'm gonna feel dumb if that's it! Another theory...
I just left a car show and looked over a 66. He doesn't have a courtesy light on the driver's side. He also doesn't have this little chromed out box on the dash that I have, but a 70 Cuda did, and it said "reverse" on it. My tranny has been changed and I wonder if my little light is supposed to go in there, and I'm missing my "reverse" sign. Still doesn't explain why it's on, but I'll look at the wires when I get home and get back to you. Thanks a bunch!
Trent

Trent Timson said...

There are 2 wires going to that light. One solid green and one solid purple. My stupid battery was dead, again, so I couldn't check the brights. I'm getting the battery tested now

Veronica said...

What you have in your car is the optional seat belt warning light. It doesn't involve any wiring as far as the seat belts themselves go, it was more of a reminder to buckle your seat belts. It would come on when you turn the key on, but, it was supposed to go out after a little while because of a thermostatic cut-off switch. Apparently, the cut-off has failed in yours and the thing stays on all of the time. If that is indeed what is going on, it should go off when you pull the accessory fuse. If you do that and it does go off, I would just unplug the power feed for that seat belt light from the three-prong accessory feed behind the dash and just leave it alone until I decided to either replace the seat belt light or fix the hole in the dash it sits in.

Trent Timson said...

I'll checl that out and let you know. Thank you!

Trent Timson said...

Is it supposed to go in that small, chromed out square opening?

Veronica said...

I just posted a picture of the light and how it is wired up. It will be the most recent thing that I've posted, right on top of the front page. Let me know if that looks like what you have.

Trent Timson said...

Yep, that's it. I'm just missing the lense. I tried to reach up and pull the wires, but I can't get my hand up in there far enough. Do I have to pull the instrument panel? I don't know why, but this scares me! Lol

Veronica said...

Yes, the instrument cluster has to come out, but, fear not. It is a very simple procedure that you can easily accomplish. I posted the procedure for that here
http://thecareandfeedingofponies.blogspot.com/2008/04/instrument-cluster-removal.html in April of '08. The thing to remember is that, if you are going to drive a 65/66 Mustang, you will definitely have to do one of two things. Pull the instrument cluster out occasionally, or, pay some guru at a high-dollar shop to do it for you. So, there's no time like now to jump in there. The first time you do this, you will no doubt be a little tentative and uncertain, but, once you have done it the first time, you will realize that it really isn't a big deal at all, and you will end up saving yourself hundreds, if not thousands, of dollars in repair bills on things you can do yourself in an afternoon. If you encounter anything that seems odd to you, please feel free to ask, and I will be happy to help out in any way that I can.

Trent Timson said...

Thanks for the help, and the confidence! :)

Veronica said...

I just added another photo to the post on instrument cluster removal. What I did was take a 66 instrument cluster and hook up the wiring from an old 66 main underdash harness. If a mouse was behind your instrument cluster with a flashlight and a camera, that's the picture that she would take. One of the wires that goes to the instrument cluster voltage regulator is not hooked up because that wire was missing from the raggedy old harness, but, it's the black/green wire that comes from the ignition switch.

Trent Timson said...

That's awesome! Thanks. I'm gonna try tackling this later tonight. Can I borrow the mouse with the flashlight and camera? Haha

Trent Timson said...

Instrument cluster is out! I think I'm just going to email you. I made a few discoveries back up in there and I took a couple pics.
Trent

Don Rokusek said...

Veronica
My original stock radio suddenly stopped working on my 65 coupe - no light, no sound. Where do I start to troubleshoot? Not sure which fuse is for radio and not sure how to check if it is getting power - I appreciate any help.

Veronica said...

The radio is powered through the accessory fuse. I use a volt meter to check the fuses. With the key in the On position, you should have voltage on both ends of the fuse. If your car came with back-up lights, that fuse also powers them, so, if you have them, and they all of a sudden quit working also, that is very likely to the fuse's fault.

Don Rokusek said...

Thanks - will need to get a volt meter! I do have backup lights but they don't work. They were repro ones and when I found they were not working I tried to unplug them and the plugs came apart - so I gave up on them at the time. Will get a volt meter and start testing. Horn also does not work. Will report back once I can check with a meter.

StangLover said...

I have a 66 Mustang convertible. I just replaced the ignition switch with a Scott Drake replacement part. Works great except the turn signals now don't work properly. When I turn on either the left or right signal they both blink like the emergency flashers are on but are very dim.

Veronica said...

That sounds like something went wrong on you during the re-installation of the instrument cluster, like maybe the ground wire from the instrument cluster to the dash brace pulled loose on you something. There isn't really anything that could go wrong with an ignition switch that would make a car do what yours is doing. I would try pulling the instrument cluster back out and have a look back there.

dale stronach said...

Is the horn on a 66 mustang fused

Veronica said...

Your horn circuit doesn't have a fuse. In 66, power for the horns comes from the headlight switch, which has an internal circuit breaker.

StangLover said...

Okay this took a while. Here is my theory. When I replaced the ignition switch it caused an increase in the electrical flow everywhere. Having already put in a new quality turn signal switch, I didn't think this was the problem. After many hours of hunting and metering I discovered someone put cheap tail light housings in the car. The two filaments inside the bulb holders were so loose and so close together I believe they were arching. I separated the two filaments, installed new bulbs and now the brake lights, running lights and turn signals work perfect and are much brighter. Needless to say I have ordered new quality tail light housings. Conclusion: If you are going to care for your classic Mustang you should feed it nothing but the best!

S Valdez said...

I need help troubleshooting my gauges on 65 mustang. I've gone through 3 voltage regulators and its driving me nuts!!!! I've isolated the problem to the source, without the gauges & sending units in the picture... One side of the voltage regulator gives me batt voltage and the other pulsating (all normal) until a couple minutes then I get full battery voltage on both sides...help!!