On my 64 C-950 - 534ci gas - The primary starting circuit is not working. with the help of the shop manual I tested back to what is refered to as the primary resistence wire. It shows it going between the ignition switch and the cylinoid.

The manual says if the voltage running from the switch to the cylinoid is more than 6.9 volts that I need to replace the wire. Is it a special wire? or is there a resister inline (I have not been able to find one)? I am hoping that someone knows about it.

The next question is if the resistence in this wire is no longer there can I just install a resistor inline and create what has been lost? If so what size and type do I need to bring the voltage down below 6.9?

 

Yes the primary resistance wire is a special wire in the harness. It should be going from the ignition switch to the coil + terminal. When you do your voltage measurements, you have to do them with the engine running, so there is current flow. If the engine is not running, the points will be open and there will be no current flow, or if the points are closed, the coil will saturate and there will be no current flow a few seconds after you turn the key on. With no current flow, there will be no voltage drop, and you will get 12 volts no matter how big a resistor you put in there.

There is a wire going from the coil + to the solenoid(starter relay). This is called the primary resistance bypass wire. If gives a full 12 volts to the coil during cranking only.

If you think the resistance wire is bad, you can replace it with a regular wire and go to the parts store and buy the large white resistor for a Chrysler product. Just make sure you mount it in the open, as it does get warm in operation.

If you are getting a overvoltage at the coil, that will not make the engine not start and run. The only thing that is going to happen if the resistor wire is gone, is the points will not last as long, and the coil may run hot. For testing purposes you can run it without the resistor wire for short periods of time.

 

Thank you. That, actually, answers a ton of questions. I am not getting anything from the coil, tested feed to it and even changed it out but same result, however, I did not check the integrity of the coil to cap and spark plug wires. I was assuming that the coil would not fire if the voltage was too high. I could not understand why, but had failed to ask that question as well. I will investigate further before I assume that the resistence wire is bad.