67 Barracuda Ignition Issue
This car has a 4 pole ballast and I get 12.5 volts at all 4 poles with the car in run position.
battery voltage at the connectors only indicates dead end, or no current flowing through resistance before the test point.
it's not a four pole connector. Someone indicated above, its 2 resistors, each with a different funtion. The 0.5 Ohm resistor should be the one connecting to the coil. it performs a similar function to the original .6-.7 ohm resistor used with the original ignition.
The second resistor should measure 5 ohms, and is not needed except with original 1970s factory ECUs.
Both the coil positive and negative get 0.632 volts with the key in run position.
Suggests that no current was flowing through, and no voltage is available in run.
I unplugged the top plug on the ballast and got 10.5 volts coming to the right side of the plug (brown and blue wire) with the car in start position.
Ok. This test seems a litle random but if the battery is also at 10.5 Volts with the key in Start, that is correct.
Pin 1 in the ECM plug gets 12.5 volts with the car in run position.
With engine not running, that is correct.
Positive side of the coil gets no voltage increase with the key in start position.
I agree with Bewey, it strongly suggests a break in the Igntion start circuit. In particular between the poiunt of measurement and the connector you measured 10.5 at with key in start.
Run a jumper wire from the battery positive directly to the coil positive and the car fired immediately.
Coil works. Ignition works when provided power.
Again suggesting a break or very high resistance in the ignition start circuit.
Here are the male and female ends of the firewall harness. Anyone see an issue here? Also, anyone know which sockets the “key on” and “key start” come through? I think we are looking for corrosion or something else that would cause a weak connection.
See previous post.
My suggestion is to undo the prettly looking wiring and redo the connections. At the same time, go to a single .5 to .6 ohm resistor in the factory location where its protected. Also keeps you from burning your hand on it.