Discharging When the Ignition Is Off

We own a 1930 Sport Coupe and a 1931 Pickup. Recently, the Coupe developed an issue with discharging when the ignition was off due to a hung cutout, which we replaced. However, we encountered a short circuit problem that caused the wiring harness to melt down from the starter to the ignition switch and amp gauge, almost resulting in a fire. We replaced all the wiring and added a new coil and a fuse between the starter and the wiring harness as a precaution. The car started but shut down during a test run. We replaced the distributor components, ignition switch, and coil but still couldn’t get power beyond the coil. We tested the wiring, and it seems fine up to the coil. We swapped the ignition wires with the Pickup’s wire, but still, there’s no power beyond the coil. Could three coils be dead (two of them new)? How can we test the coil? The wiring has been checked against the Pickup’s and appears correct. Could the new ignition switch be defective? Additionally, which terminal should the red wire attach to, positive or negative on the coil?

Answer:

It sounds like you’re facing a challenging electrical issue. Let’s address your concerns one by one:

  1. Coil Wiring: The red wire should attach to the positive (+) terminal on the coil. This provides power to the coil when the ignition is on.
  2. Testing the Coil: You can test the coil with a voltmeter. Connect the voltmeter’s positive lead to the coil’s positive terminal and the negative lead to a good ground. Turn the ignition key on, and you should read 6 volts. If you’re not getting voltage at the coil, there may be an issue in the wiring leading up to it.
  3. Potential Causes:
    • Check for loose or corroded connections at the ammeter, coil, and terminal box. Loose connections can cause a loss of voltage.
    • Ensure that all nuts on the terminal box posts are tight to maintain proper connections.
    • Examine the rivets on the bottom distributor plate for tightness. Loose rivets can cause a short circuit.
  4. Reproduction Parts: If you’ve used reproduction parts, sometimes they can have quality issues. Ensure that the new components you’ve added, such as the coil and ignition switch, are functioning correctly. A defective ignition switch could indeed cause problems.
  5. Continuity Check: Perform a continuity check on the wiring to ensure there are no open circuits. Check each wire for continuity from one end to the other.
  6. Short Circuit: Look for any potential sources of short circuits, such as damaged or pinched wires, especially near the starter area and the ignition switch.
  7. Ignition Key: Verify that the ignition key is functioning correctly and providing power to the ignition circuit.
    Condenser: Although you mentioned replacing the distributor components, ensure the condenser is functioning correctly, as a faulty condenser can disrupt the ignition system.

By methodically checking these points, you should be able to narrow down the source of the issue and get your Coupe running smoothly again. Electrical problems can be tricky, but with patience and careful inspection, you’ll likely find the culprit.

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