Not firing

Do you have a cranking problem with the starter or a crank / no-start due to loss of spark?

Here's a diagram of the ignition circuit. Chrysler has always been the leader in innovations that benefited car owners, and this is one of them. This was the world's first electronic ignition system in 1972 on Dodges and 1973 on Chryslers and Plymouths. If you see that odd-shaped plug with five wires, that is indeed the ignition module. The color of the housing denotes the maximum rpm it will work to, but for normal use, they all work the same. By the time you get to around 1980 models, they used the same five-pin module, but there will be only four wires used in the plug.

By far the most common problem was the dual ballast resistor. They often failed while the engine was idling for a long time, as at a stop light. Many people carried spares in the glove box. Check for 12 volts on the blue wire, (blue arrow), the brown wire, (brown arrow), and the green wire, (uhm, ... Green arrow). If it's missing on the brown or green wire, replace the resistor. The half that burns out is bypassed during cranking, just like we did for decades before, to make up for the low battery voltage during cranking, to develop a stronger spark for easier starting. Because of that bypass, the symptom will be the engine starts and runs as long as you hold the ignition switch in the "crank" position. As soon as you let go of it and let it return to the "run" position, the engine will stall.

You'll notice there's no ground wire in this five-pin plug. The ground is made through the module's mounting bolts, so be sure the mounting points are not rusty, and those bolts are tight.

Check the resistance of the pick-up coil in the distributor. That's best done by probing inside the five-pin connector, but don't stuff the probes in so hard as to spread those terminals. You don't want to find 0 ohms, (shorted), or infinite resistance, (open). Expect to find around 450 to 800 ohms.

I had to get real aggressive on one of my cars to get the stuck rotor off to replace it. I used a hammer and screwdriver to crack it, but I didn't realize doing that had pushed on the pick-up coil. Depending on which service literature you look at, the gap between the pick-up coil and the reluctor, (red arrow) should be 0.012" or.018". Mine was around.030" and that was enough to cause it to not generate a signal. This has to be measured with a brass feeler gauge. Standard steel feeler gauges will stick magnetically, giving a false feel.

When these ignition modules fail, it's usually that transistor mounted on it that shorts. The clue will be you'll get one spark off the distributor wire when you turn the ignition switch off. That transistor is supposed to open the circuit to the ignition coil each time it makes a spark, but when it's shorted, the only thing in the circuit that can do that is the ignition switch.

Dandy. Happy to hear you solved it, but I'm not happy with the cost. Replacement ignition modules usually cost less than $25.00 at farm and home stores, and the resistors should only be a few bucks. Regardless, I'm happy you're all set to buzz off into the sunset.