I am in the middle of re-wiring my 66 with the AAW kit, so neck deep in these details. Much of what I say you probably already know so maybe more of a sanity check. The parking lights and tail lights are one in the same. Brake lights and turn signals are separate. The fact that you are blowing the fuse as you state tells you you have a dead ground short between the fuse box and the tail lights. This also makes sense that you can light the lights up by supplying voltage locally. The wires probably run through the dash, down the driver side and into the channel under the door then into the trunk. May have been pinched or cut or whatever. Not a simple way to track it down other then tracing the wiring down

 

Alright, Here's how I see your situation. You have been troubleshooting from all angles at once. Therefore, you're chasing your tail. I'm a service tech by trade, but not on cars. But here is how I'd go about it in this case.
1) Choose one end or the other to start at. (Bulb or battery)
2) Chase your voltage (or ground) toward the other end.
3) You'll find it!

Now if I were to guess where your problem is from my couch, it's behind your fuse box. Pull it out and see if anything sticks out. But I have a few questions first.

1) Do you have 12v on one side of the fuse slot with the fuse out?
If so, I'd guess that everything from the battery to the fuse box is okay.
2) Is the other side of the fuse slot grounded?
If so, then it's time to start chasing that wire. I assume it goes fuse-->brake light switch-->bulb. The tail light wire should come from the headlight switch.
3) Are the tail and brake lights on the same fuse? If so, and both headlight and brake light switches are good, then the issue is between the fuse box and those switches.

I guess what I'm getting at is this. You need to break the circuit down into smaller sections. Check those sections, and find out if they are healthy. I like to use any place something unplugs to isolate sections. For instance, if you unplug the wires at the brake light switch, is the load side of the fuse slot still grounded? If so, your issue is now between the fuse and the brake light switch plug. If not, it's after that. Then just keep working your way back.

For now, have a beer. Tomorrow, have a plan! If you want to talk it through, PM me your # and I'll be happy to give you my opinion on things.

 

Alright, Here's how I see your situation. You have been troubleshooting from all angles at once. Therefore, you're chasing your tail. I'm a service tech by trade, but not on cars. But here is how I'd go about it in this case.
1) Choose one end or the other to start at. (Bulb or battery)
2) Chase your voltage (or ground) toward the other end.
3) You'll find it!

Thanks, very good advise. I think I started segmenting the problem at first, and then just went crazy

Now if I were to guess where your problem is from my couch, it's behind your fuse box. Pull it out and see if anything sticks out. But I have a few questions first.

Yep, I worked up to that and kept considering it. Finally pulled the fuse box and looked behind and for connecting wires. Nothing obvious.

1) Do you have 12v on one side of the fuse slot with the fuse out?
If so, I'd guess that everything from the battery to the fuse box is okay.
yep, one side 12v and the other is ground.
2) Is the other side of the fuse slot grounded?

For now, have a beer. Tomorrow, have a plan! If you want to talk it through, PM me your # and I'll be happy to give you my opinion on things.

Thankyou for the help and additional offer.

The main thing is this is rewired and the bundles are immense up behind the dash, and wrapped. I was hoping to find an obvious short with some wiggling (the short finder will screech if I find it even momentarily). Checked the obvious ends by the lights and traced it for a while. Haven't unwired the wire bundles as Id assumed Id find a wire resting against metal or a screw. I was suspect of the washer mechanism having scarred a wire. Didn't find it. More searching tomorrow, but I will look at the brake light switch to disconnect that and try isolating from there.

 

I would rather go downtown and get beat up than deal with electrical problems,,,,other than that, I could make a beer run for you!

 

Awesome response! Just a short drive for you to bring the beer. I feel I should have a group of onlookers drinking beer and cheering me on :laugh:

I rebuilt a VW engine 16 years ago. My roommates offered to help if I got beer. Then they stood there each day drinking beer and offering advise, while a friend and I rebuilt the engine. They are still good friends of mine to this day.

 

Do you have the wiring diagram manual for the year of your car? Without it you really cannot trace or test wires and be sure of what you are seeing. They are inexpensive and easily available. I completely rewired my 66FB and found the manual invaluable during the installation.

 

Of course I don't, but I'll get one and take a look. I know its the first place I should start. The wiring seems simple enough to trace, and the wiring is all labeled (just not finding the ground). I don't know if its a painless wiring harness or what is in the car, as there is much more wiring than what is needed for this car. I'll try some more and if I have no luck I'll take some photos and share for advise.

 

My first thought is that when you're powering up, you're also powering up the headlights or something and your PowerProbe can't carry that kind of load. Mine has a circuit breaker that clicks off and resets if I do that.
The PO of my '69 decided the car didn't need a dashboard not any wiring. At all. Here's me pasting together one harness out of three swap meet ones.

 

I no wiring expert but find myself constantly doing wiring

I guess in this case I would check under the step cover plate and also check where the wires pass through the lower a bit pillar and where they travel over the outer wheelhouse to make sure they are not being pinched

Someone could wiggle/lightly tug the wires from the trunk side and you can feel f they are moving in the step area

There are also some tight bends behind the kick panel where they could get pinched/cut

Best of luck and I feel your pain.

 

Re-written again for clarity

I no wiring expert but find myself constantly doing wiring

I guess in this case I would check under the step cover plate and also check where the wires pass through the lower part of the door latch pillar and where they travel over the outer wheelhouse to make sure they are not being pinched between that and the rear quarters skin

Someone could wiggle/lightly tug the wires from the trunk side and you can feel if they are moving in the step area to see if they are travelling without interference

There are also some tight bends behind the kick panel/door hinge area where they could get pinched/cut

Best of luck and I feel your pain.

 

If I have a dead short on a circuit which constantly blows the fuse I take a 21 Watt turn signal bulb with a bulb socket & 2 wires then I remove the fuse & connect the wires to where the fuse was taken out. If the bulb lights with full brightness you have a short. Trace the wiring harness tugging & wiggling along it's entire length. When the bulb flickers or goes out you have found your short.

 

Isolation is name of the game here. You need to divide the car up into 3 portions. Front harness, Dash and Rear harness of the car. You can do this by disconnecting harness connectors of the offending circuit without disconnecting your power supply to the fuse box. If that's not possible then gain access to an inductive amp clamp. The ones from sears work well and have a peak and hold feature if you don't have one. Being that the grounds are at the components you can clamp the entire rear harness with the meter. Insert your circuit breaker and observe the reading on your meter. If the short is present you will see a reading of 40-50 amps. If it doesn't move on to the next area. At the firewall gain access to the wiring to clamp. The trick here is not to wrap the battery power feeding the dash so move that one out of the way. Not knowing what what harness is in your car, am I correct assuming its GM based? If it is there is a dash illumination fuse pull it and verify its not rated higher than the park light fuse. Anyway visuals, knowing the wire color to chase and if it changes through the harness is key. Good luck!

 

Just a note, remember that light bulbs are only a few ohms of resistance when off. If you are using an ohmmeter to check the resistance between the load side of the fuse and ground it will appear to be a short circuit. I don't know the tool you using but it sounds like it was built for this sort of thing so that might not be your issue, but just in case I wanted to throw that out there.

I had a similar issue on my way but my problem was my gauge lights and radio and the lights at the shift lever. It turns out the wire feeding the light bulb at the shift lever was broken and occasionally when I would shift it would short out. I had this problem for years where that fuse would randomly blow just every 6 or 8 months or so. One day I just happen to be in my car in the garage (in the dark) looking at something completely different and when I shifted the car I saw sparks come out from under the bezel that covers the shifter. Took it all apart and there it was.

Good luck man.

 

I'm just finishing wiring up my '67 with the AAW kit and chasing a gremlin or two. You might want to pull the rear interior panel on the driver's side. When I was pulling the rear harness back there I noticed that it would be real easy to run the harness through the rear window track instead of behind it. If the previous owner wasn't careful or just pulled the wires through without removing that panel a wire could very easily have gotten stripped, pinched, cut, etc.. Good luck.

 

Well, its time for an update. Wait for it - I found a doozie!

The electrical issue stumped me and after several hours looking for the issue and trying to narrow it down, and needed to walk away for a while (work travel came up) and I didn't get back to it until today. Its been sitting in the garage in pieces with all the nice weather of summer going by. So I looked at in more detail, and realized its an American Autowire set thats in it. I pulled the seat and as much out of the way to look into it (so wish the clutch and brake pedal assemblies were out of the way). Narrowed down the issue was under the dash or forward, but pretty much had to expose all the wires exposed. I almost couldn't remember the initial problem, other than the rear tail lights stopped working and i found the fog light fuse was an issue (grounded short on one side). To make it a short story, I ended up unwrapping the wiring harness from the fuse panel onwards to trace an orange un-marked wire that came from the grounded side of the fuse panel (on the back). I found it went to the ground on the cigarette lighter??!!?? WTF? So I guess the fuse has been blown since the day I got it, and has nothing to do with the rear tail lights not working initially (which could be something simple). I downloaded the AWW wring instructions and they were awesome to call me today to try and help me out, but without wiring schematics - Id never have traced the orange wire without physically following it. How the PO put it on the ground of the cig lighter I have no idea. It was all wrapped in the back fabric tape - so you can imagine how difficult it was to unwrap and find where that wire went. I have no idea where the orange wire is meant to go, or if it came with the AWW set (although its attached like factory to the back of the panel). I took some photos but they all look like nothing - just a bunch of wires. Heres one though with the orange are and the end I pulled from the cig lighter.

So tomorrow - I'm hoping I remember how it all goes back together and can get the car started. Lots of things to put back together, including all the lights and the instrument bezel. And then try to find out whats up with lights (excluding a fuse issue).....

 

Well, the fuse panel should tell you what that wire is for. What fuse is it? It may be that it's for the lighter, but the PO just didn't know which was positive and which was ground. Now that you have that figured out, it's time to chase your 12v+.
1) 12v into brake light switch?
2) out?
3) Where's it go next?
4)...

 

jgrote; the fuse is from the fog light fuse. It goes no where as this is the wire directly from the back of the fuse panel (with power coming to the other side of the fuse). So it had nothing to do with my parking light / tail lights not working. So now I need to solve why I do not have park lights or tail lights. I do get headlights and turn signals both front and back.

Any one have any ideas on where to check? Perhaps how to check my headlight switch is working correctly? I do not have any blown fuses but I'll check again. Also with the American Autowire set up, which fuse controls all the lights? I thought it must have been the circuit labeled Fog Lights as it was the only option. Of course its not now that I learnt it goes no where. As a reminder - all lights worked correctly until one day after driving it.

 

Congrats on your find. Looks like a chevy man had his hands in there at one time by the orange wire color choice for the lighter.

 

I think AWW uses chevy parts for their rewire kits. Perhaps the fuse panel, and definitely the connection for the steering column wiring. They label their wires, but they can be hard to read when its been installed already and much of it covered or rubbed a little. The orange wire from the back of the fuse panel had no label on it - so I have no idea where that is actually meant to go. Strange that it has a connection on it and no matching home is there. I don't need it so I'll wrap it up into I decide to add fog lights perhaps. They have great install instructions available, but no real wiring diagram or fuse panel schematic so troubleshooting was a little tough. That may just be because its me. Ive got lots of wiring experience for the basics but not that great with a multi meter for advanced stuff.

 

Solved!! Its the headlight switch. What an experience. Ended up having the car non drivable for too much of this season. Good news is I found a crazy miss-wire. I don't have fog lights so never noticed the miss-wire and blown fuse until I had the issue with the lights. I figured it was a fuse and it must have been the fog lights as there was no other light fuse - and now I know its all in the headlight switch! I also cleaned up all the wiring and wrapped it with the wire wrap and protected it on any sharp edge (going into the drivers kick panel). I still need to go back out and put the bezel back in and the light lens's back on. Might be able to drive it tomorrow....

I had brake lights and turn signals working, so just tail lights and park lights were the issue. I started at each corner checking bulbs, then wiring (the power probe is so useful for this), and ended up at the switch. The light switch was solved by searching for the wiring diagram and checking continuity between the points on it (found the info on VM of course). If I slightly move the switch in and out from its middle or fully out position - I actually get the lights to work! What a sign of relief. Although now to order a new switch so I don't have to fiddle and worry they are not working. I might have solved this the day I had the issue and saved all this time if I'd fiddled with it and been able to see the lights come on and off. Best idea I found today in searching how to videos - using a large mirror in front and back of the car to see whats happening!!

Thanks to all who helped with their responses. Although no one turned up with the beer...