1985 Dodge Caravan Crank shaft

Hi brianherbert. Welcome to the forum. I think they meant the "crankshaft position sensor". That's the flat round disc under the rotor in the distributor. It's also called the "Hall Effect Switch" and is a common failure item.

While the distributor cap is off, also check that the rotor is turning when you crank the engine. If it does not, suspect a broken timing belt.

Caradiodoc

Just because the distributor shaft is turning doesn't mean the sensor is good. Check for voltage on the primary coil wire. I can't remember about an '85 model, but on the newer models there should be 12 volts on the feed wire for one second after turning on the ignition switch, then again during engine rotation, (cranking or running). If your engine uses a carburetor, you might find voltage to the ignition coil all the time the switch is on.

That Hall Effect Switch in the distributor is what tells the Engine Computer when to fire the coil. It has a magnetically-switched transistor circuit. The reluctor is a set of metal vanes that interrupts the magnetic field and induces the pulse in the assembly. Those sensors are such high failure items, a lot of people carry spares in the glove box.

Caradiodoc

Did you check for voltage on the coil primary wire?

Caradiodoc

Sorry for the delay. I'm trying to put my hands on an '85 service manual. 6 volts on the coil's ground wire doesn't sound right. The positive wire should have full battery voltage, either whenever the ignition switch is turned to run, or just during cranking, depending on the model year. The negative coil wire should have near 0 volts except when it fires; then it should go to 12 volts for just an instant.

With my fading memory, I would have to blame the Engine Computer but I'd sure like to look at the diagram in the manual first.

Caradiodoc