There is a yellow wire that comes from the ignition switch that is supposed to have a length of resistance wire in it to drop the voltage from 12V to 6 or 7V to the hot side of the coil in the RUN position. I installed a 1.6 ohm ballast resistor because I did not see the resistance wire when I rebuilt the wiring harness. Last night I was working on some interior issues and had the hood up and the key on. The ballast resistor was glowing bright red and the ceramic housing broke in two. The yellow wire coming from the switch was not hot.
Before I had the ballast resistor in line to the coil, the original yellow wire burned up and damaged the wiring harness when the trim shop left the key on overnight. It only damaged a few wires in the engine compartment and I replaced those. I have the battery disconnected.
Help, I need Help!!!
Thanks.

 

Several things here...

What kind of coil do you have? Stock or not?

For your ballast resistor that you used - what wattage was it? Or what physical size?

Lastly, the key on a points car should never be left in the RUN position when when the car is not running, as the coil can easily stay energized and pull current constantly. When the engine is running, the current is pulsed, so the resistor and coil have a chance to keep cool.

Replace your resistor wire with a correct type and lose the extra ballast resistor. If you cannot find a res wire, use regular correct gauge wire and use the correct size ballast resistor for your car. Also check the points - they may be burned, too.

 

I am using a stock coil and points. The ballast resitor is a 1.6 ohm, which is supposed to be correct for this car. The previous owner had hacked into and spliced several wires. I could not identify or find the original resistor wire, that's why I put in the ballast resisitor. The points were cooked, I replaced them. I only had the key on for about 3 or 4 minutes at a time.

 

I replaced the resistor with a new 1.6 ohm resistor (ohmed it before I installed it). I had the original and replacement resistor wired per the 1961 Shop Manual, Fig. 13-56 on page 13-26. The resistor is in line with the yellow (Run) wire and connected to the + side of the coil. It it joined there with the black (Start) wire. This matches the Wiring Diagram on page 13-5 in the 1962 Supplemental Manual, the resistor was built into the yellow wire. With key On I have 12V on both sides of the resistor with the points closed.
I re-wired the resistor per the Wiring Diagram on page 13-2 of the 1961 Service Manual, the yellow wire terminates on the power side of the resisitor and the black (Start) wire connects to the other end of the resistor and is connected to the + side of the coil with a jumper wire. I now have the voltage dropping to 6.3 volts on the downstream side of the resistor with the points closed. Progress!!!
I did not mount the resistor to the firewall before testing the wiring, but the new resistor is glowing red hot like the last one.
I have not tried to start the car yet, I'm hoping that when the engine is running the resistor will get hot, just not red hot.

 

Re-wired the ballast resisitor per the Wiring Diagram in the Shop Manual and tried to start the car. Coil was fried, no spark. Replaced the coil, car started right up and the resistor is warm to the touch but not glowing. Success!!!
Thanks for everyones input.

 

The coil opened for the same reason your resistor got hot - they are not designed to be energized continuously. 3-4 minutes on is too long. A rule of thumb would be 20 seconds or less, the time it takes to close all four power windows one at a time...
Glad it is fixed now.

 

Thanks for your help sorting this out. I am older than this car, I drove lots of 60's and 70's cars growing up. I never knew that leaving the key in the ON postion could do so much damage. The trim shop, having left the key on all day or night, frying the yellow wire, the points and the coil, is what kicked off this chain of events. Restoring the wiring harness and re-wrapping it was no fun. And, I did not think about it at the time but, the whole car could have burned. That, is why I hate electrical problems and appreciate your's and everyone elses help.

 

Glad I can help...

If you ever take it to a shop again, put a big red sign on the dash that reads "Do not leave key in run with engine off, stupid!"
Okay, maybe omit the stupid part, but they should get the drift anyway....