Confusing electrical gremlins

[EonicDuster]

Hi, everyone.

I've done a lot of searching on the forums, I've found pieces of information to the problems. I think im on the right track. The car is a 1970 Duster (production. 12/69) 225/ A904 / A/C.

Im pretty sure the harness is toast or at least damaged (fuse block accessory melted, massive bundle of butt connectors under the dash, brake switch power terminal burnt and shorts when hazard is bumped, headlights only work when hi-beam switch is on) I load tested the alternator it outputs 13.3 to 14.2 regardless the load. Recently all the lights have been dim when at idle, but brighten once moving, and the dash lights flicker all the time (ammeter hovering in the middle, occasionally going all the way to + and all lights bright as day).
I went to drive it last night, started it up, turned on the headlights, they flashed and went out. I shut the car off and it lost all power, I had a spare ballast resistor, replaced it and It has power back again, but still no headlights and flickering dash lights. It does have a amplifier and equalizer that appears to have been tied into the accessory circuit.

I honestly have not probed many connectors under the dash because they are very brittle, and moving them tends to cut off the brake lights

I'm not very skilled in repairing electrical, but I have a decent understanding of the theory. So my question is, does it sound like the harness is butchered beyond repair, along with a headlight, brake switch, or intermittent short or is it something simpler I'm overlooking?

Forgot to mention I purchased it from a eldery man who owned it for the last 41 years (bought it last November). He seemed to do most of the repairs himself.

Thank You
*Edit for grammar and pictures

 

[halifaxhops]

Hate to say this sounds like at least a new dash harness is in order before a fire.

 

[Blind Squirrel]

I was almost expecting to see a .22 shell stuffed in the fuse block, or at least some double mint gum wrapper foil.

Bite the bullet and front for a new harness for sure.

 

[Kendog 170]

I don't know if this 72 harness will work but I see it in the Classified section . Maybe someone here knows.
[FOR SALE] - Dash wiring harness

 

[RedFish]

ballast resistor is not related to headlights or all power lost. You may have bumped a failing connection at fusible link or bulkhead connector while changing ballast resistor. or maybe not. Some of these harness connections can fail when the get too hot and work again once they have cooled. That ignition switch connector with large pink wire is one example. So replacing a chopped up dash harness is a start. You'll need to check a bulkhead connections, charging system, etc... also. Good luck with it.

 

[67Dart273]

I see at least one fuse clip in the fuse panel is junk. Hard to say "I ain't there." But once things get bad enough, it gets tough. A different harness just might be the thing. Just be careful you don't trade one problem for another.

 

[Kendog 170]

each end of the fuse box has rusty terminals. You may have a water leak (windsheild ?) thats dripping on top. I just discovered this past summer mine is. Going to reseal windsheild gasket with bedding compound.

 

[EonicDuster]

Im not with the car right now (at work). I dont think it has a water leak, I accidentally left it out in the rain and the carpeting was dry and no sign of condensation.
I'm glad I was on the right track with figuring the harness was bad. I noticed on a few wires coming off the pos terminal and bulkhead connector that it looks something was cut out and tied back together and wrapped in tape.
I'm currently rebuilding the exhaust, trying to repair it piece by piece (first project) and didn't want to condemn major parts before consulting the experts

Thank you again, y'all awesome

 

[Mattax]

After working on exhaust, electric will seem like a breeze. Well maybe not quite but exhaust, especially without a lift is brutal. Most of the time its worth doing it from the manifold back because expanding pipes that have been clamped is difficult to say the least.

Back to the questions raised..

I load tested the alternator it outputs 13.3 to 14.2 regardless the load.

Tough love here: This showed the regulation is working. The alternator does not output voltage. The output is current (moving electrons) at a voltage. Together the result is power. Even when there is no current, there is voltage at the output terminal.
This is important for your troubleshooting. When measuring alternator output, both a voltmeter and an ammeter on the output wire are needed. Don't worry about getting an inductive ammeter to do this because so far alternator output doesn't seem to be the issue.

Recently all the lights have been dim when at idle, but brighten once moving,

This was common with A-bodies. At slow idle the alternator can't produce as much power as at higher rpm. The alternator may be maxed out at idle speed, possibly because hte battery is not fully recharged. We'll come back to this as it may be it may be related to the other problems, but may be not.

and the dash lights flicker all the time (ammeter hovering in the middle, occasionally going all the way to + and all lights bright as day).

Flickering could be loose wiring anywhere in the circuit including a ground. If its only the dash (not the dome or sidemarkers) then that will help narrow down where the problem(s) are.
Ammeter shows current flowing in or out of the battery, except what goes directly to the starter during start. While the starting the ammeter should go slightly toward discharge. Immediately after starting the ammeter should go about halfway to Charge, and then quickly return to the middle.

This is a diagram of the basic circuits. Notice the car's ammeter is in the battery feed. It doesn't show the alternator's output. It only shows the portion of the alternator's output that is being used to recharge the battery. Also notice that only some of the sub-circuits have fuses. A couple are full time. Two or three can only get power when the key is in run or accessory positions.

occasionally going all the way to + and all lights bright as day).

This is a big clue to one of the problems. When the ammeter pegs in either direction there is more than 40 amps flowing to or from the battery. This is more than the wiring can survive for for more than a very brief period of time. Pegging positive mean the battery is sucking a massive amount of power. Its either very undercharged and the alternator is now turning fast enough to provide over 40 amps, or its overcharging because the alternator is producing power at an excessively high voltage. Since the lights get very bright at the same time suggests system voltage has jumped - perhaps higher than 15 volts!

 

[Mattax]

I went to drive it last night, started it up, turned on the headlights, they flashed and went out. I shut the car off and it lost all power, I had a spare ballast resistor, replaced it and It has power back again, but still no headlights and flickering dash lights. It does have a amplifier and equalizer that appears to have been tied into the accessory circuit.

100% agree with Redfish. Ballast resistor not related. The ballast resistor is simply used to drop the voltage as a form of current control to the coil when the engine is running.

Headlights could flash off due to a failure in their wiring, or the circuit breaker in the headlight switch opening.
The headlight circuits in these cars (a-bodies) are problematic. They were made with wiring that was just adequate for the 6012 bulbs it came with. Most replacement bulbs today draw more current, and oxidation and vibrations often make the connections that much weaker. Finally whenever a lamp is offered electricity at higher voltage, it will draw more current. Start with checking all of the connections; at the lamps, at the dimmer switch, at the headlight switch, and finally, at the bulkhead. Also check the grounds.

Complete lack of power suggests the battery feed or ground is damaged or loose. Check the fusible link along with the rest of the battery feed and the battery grounds to engine and body.

I'm going to suggest having your portable voltmeter handy to measure the voltage differences at a couple points the next time you see the lights brighten up. Again be very careful - if the ammeter is pegged shut it down.

I honestly have not probed many connectors under the dash because they are very brittle, and moving them tends to cut off the brake lights

Without being there its hard to say more but if you can't back probe a terminal connections without the connector cracking that's pretty bad.

I'm not very skilled in repairing electrical, but I have a decent understanding of the theory. So my question is, does it sound like the harness is butchered beyond repair, along with a headlight, brake switch, or intermittent short or is it something simpler I'm overlooking?

The only butchering I see in the photos is what looks like the column connector. Those seem to be often problematic, especially in the early 70s.
Notice in the diagram that all of the current for powering ignition and accessories runs through that connector. However lights do not.

I noticed on a few wires coming off the pos terminal and bulkhead connector that it looks something was cut out and tied back together and wrapped in tape.

So here is probably the place to start hunting.
There should be one, and just one, wire from the positive battery terminal other than the one for the starter. Check the whole length especially the connections. The fusible link is a smaller gage wire and purposely intended to be the weakest section.
The alternator output wire sometimes carries a lot of current. The standard connection through a '70 bulkhead connector is the weakest connection in the line.

 

[Mattax]

There is another possible gremlin we havent discussed. It has to do with the voltage regulator circuit. As a Dec '69 build I don't want to guess which system is on your '70 as if guess wrong it just more info you dont need to be absorbing at this time. Post some pictures and we can come back to that.