Last night I noticed that my headlights on my 65 Roadster were not working. The courtesy lights and brakes lights are also out. I pulled the fuse for the brake lights and courtesy lights and it was blown. I tried to replace it but it immediately sparked and blew The headlights open, the tail and parking lights work, the light indicator on the dash lights up, and the directional signals are working. I am not an electrician by any means so any help would be appreciated.
Don

 

Do you have a schematic of the electrical system and a multi-meter? Know how to use the meter? Don't have mine here on the road but think the tail lights, courtesy lights, and parking lights are on a different circuit. Lots of times when the head lights have issues, the dimmer switch is the culprit. If you have a meter, we can most likely talk you through testing it.

Geek

 

I do have a schematic of the electrical system but must be honest, don't have a clue how to read it. I do have a simple volt/ohm/A multimeter.

 

Also any idea of the sparking in the fuse box and instant blowing the fuse when I try to replace the brake light/courtesy lights fuse?

 

Yes, you have a dead short somewhere in the circuit.

 

Any idea on where to start to troubleshoot or take it in to a professional?

 

If you feel like digging into it, you can follow a wiring diagram to see what all is connected to the circuit, and systematically start disconnecting everything on the bad circuit until the fuse stops blowing

 

Thanks, that sounds like a plan. Any idea on the headlights not working?

 

The other thing you can do is pull the bulbs out of the effected sockets. See if the fuse still blows. If not, you can replace them one by one until you find the source. Sometimes corrosion can grow in the socket and arc over.

The headlights are on a self resetting breaker. I would first check the grounds. There is a ground wire on drivers side, engine side of the radiator support (For the headlights). There are also chassis grounds (6 I think) under the car. Check them as well. They are bare solid copper braided wires. On my coupe with under car exhaust, there are 2 at the Trans mount / exhaust support clamp area. There is one near the base of the drivers door hinge pillar under the mud shield. I would check any black wire that is bolted/screwed to the chassis or frame of the electrical device. Bad grounds are a common problem. Make sure they clean, and there is metal to metal contact.

I usually clip the round terminal off (if enough wire is available) and re-crimp a new terminal on with fresh wire exposed. Then heat shrink the crimp. Clean the respective contact surface and coat with dielectric grease.

I use a small 45 degree air driven grinder with a small wire wheel on it to clean the contact surface.

A 5.00 dollar volt tester and a single wire test light are very helpful for diagnosing problems.

Also check to see if someone has cut or molested the wiring. Look for wire nuts (Those twist on caps that bind wires together). If you find any, remove them, crimp with a splice joint, and heat shrink the connection.

Also look for those cheap plastic covered splices. The connection rots out because it is exposed.

Mark

 

What he said (sure, it's easy to agree with a lengthy, well thought out answer).

As for the headlights not working - I wonder if it could be a bad headlight switch.

 

You can remove the dash switch for the headlights. Use an OHM meter to check for current passing through the various switch functions.

The first pull of the switch should light the running lights
- Front two amber lights
- Rear two red lights
- Dash lights

The Second detent should of course turn the headlights on, and shut the running lights off, and leave the dash lights on.

Twist the **** to the left past the detent to activate the dome / courtesy lights.

The Dome / Courtesy lights (the two on the kick panels) and the cigarette lighter are on the fuse labeled "COURTESY" IIRC.

The Turn / Brake / Back Up lights are on there own circuit labeled
"TURN BRAKE" IIRC

If the turn signals light up, but do not blink, the flasher is bad, or you have one of the turn signals, front or rear not working or a bad bulb.

And last but not least, check the dimmer switch on the floor. Check to see if high or low works or if they are both inop. That switch can go out and take everthing with it. You can pull the switch, unplug the connector and use a jumper to force a connection to get the lights on for trouble shooting.

I am at work and away from my books.

Hope this helps.

 

The only wire nuts I have found were for the speaker wires which are not connected to any electrical circuit. I will check the grounds that you suggested and pull out the bulbs one by one to see if I can pinpoint the problem. I did add courtesy bulbs yesterday that were missing but the doors were closed when the fuse blew so I didn't think that could be the problem.
Don

 

Well, that's interesting. If your headlight switch was turned to have the courtesy lights on, and if the courtesy light circuit is bad, then installing bulbs into sockets that were mysteriously empty would do it.

Try removing the courtesy light bulbs and then seeing if a few blows.

 

Check the bulbs that you put in. It is real easy to put in the wrong bulbs which will blow the fuse every time. (No need to ask me how I know). I forget if the correct bulbs have one "nub" or two. A quick look into the socket will tell you what you should have. I think you just used the wrong bulbs.

 

I was messing with the courtesy light switch last night to see if I could get anything to work and there was a bulb in the passenger side front courtesy ( and still is there). I will take that out and try to replace the fuse again. It's dark here and the trick or treat'rs are here every two minutes so it will probably be tomorrow morning before I can troubleshoot. Check the thread tomorrow and I will update you on the progress. Thanks again for the help and suggestions.
Don

 

Shouldn't be too hard to find.

The best way is through the process of elimination. Determine if it is the rear or front harness that contains the short. Helps narrow it down.

You can use you multi-meter and set it to "ohms" at about 1k or lower 100ohms. Can't hurt the meter regardless of ohm setting so no need to worry.

Disconnect your battery (either or both terminals).

Pull the front headlight harness out. Facing the firewall it is the harness plugged into the right side of the connector.
Using the meter touch the RED probe to each tab (there should be 8 of them) and put the BLACK probe on a GND source such as the engine block or coil holder etc.
Bulbs are plugged in so there will be a circuit (~600ohm or so) but if you see any that read very low ohms then that is the circuit shorting (ie right headlight, left headlight, parking right, ...).

If the Ohm readings are all similar then repeat for the rear harness connector.

If you want to do it brute force to determine front or rear you could do similar to the above but plug in a fuse each time you pull either the front or rear harness. Connect the battery and determine if the front or rear is the problem. Then use the ohm meter to isolate exactly.

Good luck.

John

 

Thanks to all for all the info and suggestions. Sounds like I have my work cut out for me today. I'll update later.

 

I'll check but these just came from LIC and they are suppose to be the correct bulbs for the coutesy lights and a seperate one for the glove box. I just restored the glove box and switch. The old switch was just hanging behind the glove box with no bulb.( maybe for a reason).

 

The bulbs for the two kick panel courtesy lights have two nubbins or contacts at the bottom of the bulb housing. The courtesy lights are positively grounded back to the wire harness, then splits out somewhere to go to the switch in the door hinge jamb. Which means that the socket is not grounded to the frame as most single wire sockets are. So if you put a single contact bulb in there, it will make a contact across the 2 leads in the socket and blow the fuse.

Sounds like you have 3 problems, the courtesy lights, brake lights, and headlights.

Fix one at a time. Electrical problems are easy to get buried in if you change too much at a time.

 

Here is where I am so far with all of the suggestions.
Pulled the courtesy lamp bulbs one at a time ( and the glove box bulb) and each time tried to insert the fuse. Each time it sparked. I thought I had something because the courtesy lamp socket in the back ( convertible) had a loose wire. I disconnected each bullet connection to that socket and seperated them and tried a fuse but again it blew. I was about to disconnect the front harness to test each circuit and noticed that what looks like on the wiring diagram to be the neutral safety switch has a wire connection screwed in on top but no wire ( broken inside connection). There is another wire connected under the same screw that seems to come from the rear wiring harness. I do see a wire coming out of the firewall ( 600 volt, labeled 14AWG that goes nowhere. Is that the wire that broke from the top of the switch? Any experts out there? I can send a picture is that helps.
Don