Ok fellas, here's my conundrum (1975 Duster)

So last week I was replacing some parts in my driver's side door. So the door was open for a few hours in total (don't get me started -no pun intended- lol). Well, I go to start the car yesterday for my weekly drive and nothing happens. It's the classic dead battery: no lights, no nothing, no turning over. Well the battery that came with the car had a big yellow "USED" sticker on it, so I thought, well, it's probably time to get a new battery anyway. Well, today I install the battery (720 cca) and it starts just fine. Well, I turn it off, go upstairs and decide I want to adjust that fast idle like I mentioned last post. I come down, adjust the idle, turn it off, turn it back on again for whatever reason and let it run for a few minutes. Then go back upstairs to call it a day. I then come down to go drive somewhere, and it's dead again: no dash lights, no turning over, no nothing. What's could be the problem?

Recap:

1. car had the dead battery symptoms (no lights or turning over)
2. replaced the old battery labeled USED with a new battery at 720 cca.
3. Car cranks and runs fine. Cranks several times (don't know if that's relevant).
4. Car has dead battery symptoms again (no lights or turning over)
5. Took the battery to O'Reillys and they tested it and it was good and had charge.

Additional: car wouldn't crank when trying to jump off from another car before the battery was taken to be tested.

So where would you start?

Thank you for all your help!

Loose battery cables, failed battery canles, poor ground, failing ignition switch...

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Casually looking for a Clifford hyperpak intake for cheap.

Would a failing ignition switch cause the headlights and dashlights to not come on?

The last time this happened to me it was a failed ammeter guage. By passed it and everything worked fine.

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62 Val, 66 Dart, 16 Ram 2500 Mega

Possibly, or a failing headlight switch.

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Casually looking for a Clifford hyperpak intake for cheap.

Ammeter worked fine before, although it did look to be to the right of middle (don't know if that has any bearing on things) after I put the new battery in. Terminals look fine, going to clean up the grounds tomorrow and check out the connection to the starter.

Made a late night 3rd battery switch with a new one from the store. Still no nothing. Cleaned up the terminals with spray and inspected the cables at the terminal end, and they looked ok.

Going to clean up the terminals at the block and at the starter tomorrow.

What else does the battery connect to that I should check? What's between the battery and starting?

Thanks!

If all else fails, I'll change out the cables.

You need to start troubleshooting at the very least with a 12v test light. You need to start probing what does and does not have power going into and out of the ignition switch, the headlight switch, etc... Tracing electric issues cannot be done efficiently or effectively by guessing.

The main (+) feed from the battery goes to the bulkhead, then to the ammeter, then to the fuse box where it breaks out to feed to other circuits. The common starting points when diagnosing electrical issues in old Mopars are (1) clean both halves of the bulkhead connectors; (2) clean and possibly bypass/replace the ammeter; (3) check the functioning of the ignition switch, check the connections at the fuse block; (4) start probing and tracing the circuit having the problem.

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Casually looking for a Clifford hyperpak intake for cheap.

Any photos of a bulkhead connector or the ammeter?

OK- the ammeter is a gauge in your dash. The bulkhead connector is the big plastic clump of wires on your firewall above the steering column.

I am not being a jerk when I say that if you can't identify the ammeter or the bulkhead connector you need to stop working on your car until you have a factory service manual. You need to know what you are doing before you start throwing parts at it or taking things apart willy-nilly. A good service manual is the most important tool you will ever purchase to work on your car.

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Casually looking for a Clifford hyperpak intake for cheap.

GYYAARRRRD!!!! SO RUDE!!!

Just kidding. I understand what you mean. I'm not a mechanically inclined person, but me being 32 and married, I need to learn because we're going to have a cars for a long, long, long time, and service shops get expensive fast!

I got a Haynes manual, a Chilton manual, and I scored the 2 service manuals for 1975 off of ebay for a whopping $18.

Gotta learn sometime, I reckon!

Way to go, Sir! The factory service manuals have a wiring diagram section- learn to read it.
I know that the "start-run" relay will shut down the ignition, and maybe the starter too. (REED??) That relay is somewhere on the left fender well, not too far from the battery. But the best place to start is to clean all corrosion from the battery & ground cable connections, both ends. Also, if the battery cables have been "repaired" using the bolt-on style clamps to the battery posts, then take those bolt-on cable ends apart and clean everything, clamps and wires, with course sandpaper. Reassemble with grease (Vaseline petroleum jelly) to keep moisture out. The little electrons can find their way through the grease. The start-run relay can be carefully pried open and the internal contact points cleaned of corrosion, sometimes successfully.

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"Louise", a 1976 Dart Custom project, (now sadly reverted to being just an "organ donor" to our other project Darts.)

If one were to compare service manuals to general literature, Haynes and Chilton's manuals are equivalent to the "Little Golden Books" series while factory service manuals are equivalent to the Encyclopaedia Brittanica. Seriously, Chiltons and Haynes are OK as step stool or door stops, but if you are serious about learning how to work on your car and have already purchased them, just go straight to the factory service manuals. And I say that as a mostly self-taught mechanic who started learning on Haynes and Chilton's manuals and eventually found my way to factory serice manuals.

The starter relay will cut power to the starter motor, but won't kill all power to the whole vehicle. The complaint is that all power is lost- dash lights, headlights, interior lights, etc... The battery tests as a good battery with a charge, so somewhere between the battery and the fuse box there is a break in the power supply. Battery cable, ground, bulkhead, ammeter, ignition switch are just about the only things that full current flows through.

I can take a look at the wiring diagram for my brother's 74 Duster tomorrow. That should be close enough to a 75 Duster.

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Casually looking for a Clifford hyperpak intake for cheap.

Thank you very much for all your help, by the way. I got a digital multimeter while I was at the parts store last night. Looking at the wiring diagram from the service manual under the electrical section, it shows that I can test the ammeter by disconnecting it from the alternator and running it through the multimeter.

I was looking at the wiring diagram for my brother's 74 Duster. The starter motor and starter relay are fed directly off the battery. Since you have no power to anything, and the starter motor does not even attempt to engage when you turn the key, and since the battery has tested to be a good battery and it has a charge, I believe that your problem lies in the battery cables or in the power distribution from the ignition switch to the starting circuit.

I forgot to mention the fusible link in my previous suggestion.

Try jumping the two terminals on the starter motor. If the starter motor engages the engine and spins, then you know you are getting power from the battery to the starter motor and that the battery cables are OK. If that test checks out OK, then you need to get a test light and just start probing the (+) feed starting at the battery until you find the point where you are losing power. Probe the (+) feed on both sides of the fusible link and on both sides of the bulkhead connector. Probe the feed on both sides of the ammeter.

You can TEMPORARILY AND FOR TESTING PURPOSES ONLY remove the ammeter from the circuit but removing the wires from the back of the gauge and connecting them together using a small bolt and nut through the eyelets on the wires. Be sure to securely wrap this connection with electrical tape to prevent any accidental grounding of the terminals against a ground on the dash frame. You must properly reconnect these terminals to the ammeter once you have found the break in your power supply and have repaired it.

From the ammeter move forward to fuse box, the ignition switch, and the headlight switch.

The break in your power supply should be at or ahead of the ammeter since you are losing power to the entire vehicle.

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Casually looking for a Clifford hyperpak intake for cheap.