I will give you as much info as I can on the short time I spent with the car this weekend.
An older gentlemen that I know stopped by this weekend with his 69 Charger.
Car was last driven about 20 years ago. He is trying to get it safe so his grandson can take it to the prom.
The car has a non matching 440 that was a replacement engine at some point in its life.

The problem is the car runs fine with its lights on for about 10-15 minutes then something appear to be heating up and shutting off the lights, all of the lights. They will come on an off actually.
After the car cools down the lights work fine for about 10 minutes again.

This is what I know after spending a short time with the car.
The engine harness is the original harness that is a total mess. I am quite surprised it runs so well. There are splices and wire nuts everywhere from the horns to the alternator and about 6 at the bulkhead.
The front light harness is original too and has a couple wires that are very poor.

The car is running an electronic distributor that was converted over last year. They stated they took the insides out and changed it to electronic.
There is no ecu box and its still retains the original voltage regulator. I had no idea that was even possible.

The alt was putting out about 16 amps with a battery that has been sitting all winter with only a 10 mile drive on it to my garage.

The headlight switch was very hot to the touch when they arrived.
The dimmer switch is new.

So I recommended getting two new harnesses asap, engine and forward light at a minimum.
My question is what do I tell him to order for an engine harness with the distributor he is running.
I can have him get a electronic conversion harness but how is he running an electronic distributor with no ecu box currently.

Secondly what on this car would heat up and make the lights go out.. Would the headlight switch do that if it gets too hot/overloaded.
I am afraid he will buy the harnesses (which he must for safety at least) and will still have the light issues.
Thanks for any advise!

Something is drawing too much current and tripping the factory circuit breaker. Your description of the wiring is a clue
Step #1 Get someone who is familiar with the cars and electrical portion of them.
Step 2 Start with new harnesses straighten out the ignition system. Lot's of choices there.

Might be a good idea to park it and keep the battery disconnected in the mean time

A bad high beam dimmer switch can cause issues & they are in an area known to get wet at times if the wiper pivot seal fails.

I've had my hand all over these car but had no idea there is was a factory circuit breaker. Where is this located. Why would it not blow the fuse?
My hope was that once these harnesses are replaced along with the ignition cured that the light issue will be a thing of the past.


The dimmer switch is new Barry and I checked it and surprisingly not melted like many I have seen.
The headlight switch connection has evidence of a few hot trips. It is not destroyed but disformed a bit in a couple areas.

Had the same problem with my 68 charger and my 79 Cherokee chief. I even had a new harness in the charger. Circuit breaker is in the switch, and gets more sensitive with age. I just installed a headlight relay kit in both vehicles to get rid of the problem. No more problems, plus no more fire hazard and brighter lights.

Ahhh. So we'll put some new harnesses on for him and hopefully he will be in good shape.
Thank you very much for the info.
Had no idea the switch would overheat and shut the lights down!

. Check if (newer) bulbs I have had that problem as well after putting in new headlight bulbs from parts stores, the replacements have been halogens for years now and I think they draw more and the old wiring cant take it.

They are new!

I'm thinking bad headlight switch is the culprit here (the circuit breaker on/off function is classic bad HL switch).

The headlights are on a circuit breaker in the headlight switch.
BUT. All of the other lights are fused.


Oh. Boy.
There are two super critical connections at the bulkhead. And a handful of others that have limited protection.
Super critical are the power feeds. One from the alternator, the other from the battery. All of the power flows through one or the other depending on the situation.
They join together at the main splice inside the car.


They probably used a Pertronix Ignitor 1 or 2. If so, there will be a power supply wire going to the distributor. My guess is they tapped into the ignition run circuit, on or near the ballast resistor.


That's not good. Too much current or poor connections.
Too much current could be due too high of voltage in the system.
Measure the vltlage at the alternator output stud and a few other locations such as at the ignition run connector on the ballast, and battery. (While the engine is running)



If its the petronix, you'll just need to add a power wire.


Take the bulkhead connectors off. Make a diagram of the colors/size location. Or better, check it agains the factory diagram. Then one by one, remove the female terminals and make sure they are not damaged around the crimps. Clean each one, Make sure the barb is raised and reinstall. Gently tug to be sure they don't back out.
Wouldn't hurt to check the condition of the fuses.



General Power Schematic for late 60s

just because the headlight dimmer switch is new, doesn't automatically rule it good. most now, are offshore produced.
still sounds like the headlight switch is the main problem.
member crackedback [if my old mind remembered correctly. if not, please accept my apologies ! ] makes a GREAT relay kit for the headlights ! easy to install with his instructions, and reasonably priced as well. i used his kit on my buddie's 72 duster, and it worked GREAT !
for the money, you can't buy the material used in the kit and build one yourself unless you use CHEAP material and components, which his are all High Quality.
wiring can be problematic, but if you take your time, draw diagrams to help you keep track of the wires and the positions they go in, and use quality replacement parts, you can do a successful repair !

Great information everyone.
One last question. So would you agree that I should have the owner order a factory point style harness and just run the power to the petronix ignition.
If so would petronix ignition still require an electronic style voltage regulator? There is a factory point style regulator with the petronix now.

No, I would purchase another headlight switch. I dont care for the electromechanical regs but for now all is good in the 'hood until you pull the light switch so I would resolve that .

He's got to get new wiring as this car is going to burn to the ground if driven with this wiring..
Remember the alt is reading 16 amps at the terminal as well.

The gage marked 'alt' does NOT read at a terminal.
It is an ammeter. It deflects to show how much current is flowing through its internal shunt.
It only deflects if current is flowing through it.
Unless someone has wired new loads onto the battery, the ammeter shows the flow rate the battery is discharging or charging.
When the battery is charged and the engine is running, the alternator should handle everything and the ammeter should show zero.

The system voltage needs to be checked at several places to be sure the regulation is in spec.
* Alternator output stud.
* Regulator ingition connection
* battery Pos.
Also check that there's no voltage drops in the ground. Voltage drops only occur when current is flowing though a resistance, so you'll need to turn the heater fan or lights on for this to be a helpoful check.

As far as the pertronix goes - assuming that's what it is. Its probably OK with the electromechanical VR, but you can check with Petronix. It's probably in the instructions if it can't handle the noise of a mechanical regulator.

With a replacement engine bay harness, you still will need to check the firewall connectors and also the headlight switch connector as described previously. Too many unknowns here to assume everything else is good.

Ok. Will do. Thanks for the info and I will get some numbers on those areas.

It may be fine and just a low battery.
But here is a scenario when there are bad connections or terminals.
Lets say all of the bulkhead connections have lots of resistance.
As a result, the voltage regulator sees a lower voltage than the alternator is producing.
So the regulator lets more power go through to create a stronger magnetic field.

Result is something like this.
The alternator is putting out power at higher voltage. Lets say 16.5 Volts
Some of the voltage drops as current flows through the resistances.
Regulator lets enough current through that it sees 14.0 Volts
The battery, like many electric devices, draws more current at higher voltage.
While it would have drawn no current at 14 Volts, at 15.5 Volts, it draws 16 amps.
It can't transfer any more electrons chemically, so it turns that energy into heat and boils off the acid.

There is good information and some not so good information in this thread.

Barry's recommendation about the dimmer switch is spot on. Many Mopes have had that issue.

Robert is also correct.
Bulkhead connectors are also a common Mope issue. The Packard connectors in the bulkhead are only rated at 40 amps when brand new. Add a bit of corrosion, 50 years of time and that shiny brass connector that came from the factory is heating to an alarming degree.

The splices in the harness are also alarming. Wire nuts and splices can make for "ohmic" connections meaning they also can heat up and cause flaming issues. There should be no splices in the heavy gauge wires such as the alternator post, headlight wires and fusible link.

One piece of bad information is on Halogen headlights. They are much more efficient that the tungsten ones the cars came with. Halogens put out more lumens per watt and therefore draw less current than the old ones did. That is why the industry went to them.

All in all, you have a lot of trouble shooting ahead of you. Go for the easy stuff first but do not skip anything, even if you find the problem, there could be something else lurking another wire bundle.

Craig

re: Headlight draw. Correct for industry standard replacements.

1968
4002 nominal 37.5 and 50 Watts
4001 nominal 37.5 W

1970 up
4000 nominal 37.5 and 60 Watts
4001 nominal 37.5 Watts

Phillips Lamp Guide Replacement Sealed Beams Cross ref.
4000 ->H5006 nominal 35 Watt and 35 Watts
4001 -> H4001 -> H5001 nominal 50 Watt

AFIAK those are all nominal power draws at 12.8 Volts.
With lamps, increasing supply voltage will increase the current draw.

On changeing the bulkhead terminals (packard 56), on the male ones, one leg is open but you can tell which one it is when they are in there but push both of em inward slightly & you will see which one is moveable & push that one in a bit till you can pull the wire on it out the back side. On the female ones reach in with an eyeglass mini screwdriver & flatten the "tab" till you can pull the wire with it out the back side. Dont force either one, when you have it bent just enough/right amt the wire/terminal will easily pull out the back side. New terminals: raise the tab on the female ones a bit to where it "snaps" into place as you pull it via the wire backwards into the bulkhead. the male ones, no prep just pull em backward till it locks. Take a spare male one (buy an extra) & fit it into the installed female ones before installing em to insure a good fit on each one (bend the curved edges as needed) then see if the bulkhead halves fit together (easy at first) as all of em need to line up dead on. Some have recommended a dielectric paste (not sure on that), others will advise. NAPA has the terminals for 99 cents ea (pricey) 725145 and 725147 or they are online in quantity for cheaper. I am in favor of running the (2) main in/out heavy wires straight thru & soldered/no terminals (Nachos' bulkhead parallel bypass) & you leave some length of wire behind the dash behind the bulkhead on those (2) so if you have to pull the forward bulkhead half forward in the future it will pull that 6" of connected wire(s) out with it.