I have a 70 L46.
Both wires to the positive side of the coil are covered in white insulation type material. I touched the one that goes into the wiring harness (Ignition circuit), and it was really hot. I know it is a resistor wire, whose funcion is to lower the voltage going to the coil after the engine starts). Some of the insulation material is brown from overheating. Is this normal, or do I have a problem?
The other wire (that sends 12V from the starter solonoid during starting), does not get hot.
Thanks for any help.

 

Was this with the engine running or just ignition key turned to on ? I do recall it being hot sometimes with the ignition on but don't remember it being hot while the engine was running.
Seems I remember it will get hot depending on if the points are open or closed.
If 69427 sees this post he can tell us , as I'm sure others can as well.

 

It's when the engine is running.
Thanks.

 

Roger
I thought the resistor wire was part of the engine wiring harness. I was recently told that it is actually under the dash, between the ignition switch and the firewall connector. Can anyone confirm?

 

It is possible that the resistor wire got replaced with some 'regular' wire. The purpose of that resistor wire is to limit current, not [specifically] to reduce voltage. If you don't have that resistance wire in place, perhaps it is drawing too much current for that wire. Just a thought...

 

I have only seen the resistor wire in the engine harness. I believe you can see it right at the coil,look in the crimp where the 2 wires are together,the resistor wire is a solid single strand wire.
I'm not sure what its made of but I don't think its able to be soldered.

 

I believe you are right. I have a replacement Lectric Ltd harness and noticed the cloth insulation with the red stripe has become frayed and missing where the wires go thru a grommet in the ignition shielding. The white wire underneath has some fine printing on it, so I believe that is the resistor wire. Also noticed my grommet is hardened and has a split inside the outer groove, allowing the wire to make contact with the shielding. I think I have just found the cause of all my ignition problems. Right now the car is running good with new points and condensor. I am seeing 11.06 volts at the coil positive with the engine running, using a correct Delco reproduction coil. Hopefully my resistor wire is still okay and and appears to be dropping 3.35 volts from a 14.41 system (alternator output) voltage. I am going to find a new grommet. Sheesh.

 

It's a little hard to make out in this pic, but the coil wire is the yellow wire sticking straight out from beneath the wiper motor (has a right angle open ended terminal crimped on the end).
This is a brand new Lectric Limited engine harness for a 73.

 

Kevin
There are two white braided wires held together by a crimped connector at the coil positive, as Roger said. According to the '69 AIM, the one with the wider yellow-striped braid (identified as Y) comes from the starter solenoid. The one with the thin red-striped braid (identified as W-R/B) comes from the firewall junction box. This is evidently the resistor wire.

For the OP...have you checked your voltage at the coil when running?

 

Not yet, but I suspect it has dropped the voltage because the engine runs great after it is hot. Previously, the engine died after about 15 minutes of driving. The prior owner had a Mallory electonic ignition distributor with a regular coil. He had wired the positive side of the coil directly to the fuse box. The coil was getting a continuous 12 volts, causing it to get too hot and short out. After it cooled off, the engine would start again.
I found an original distributor here on the forum, bought a new coil, and found the 2 original coil wires with the white insulation wrapping on them (that weren't connected to anything). They were still crimped together with the original "fork" style electrical connector. I fastened this connector to the positive side of the coil. The other end of one of the wires went into the wiring harness. The other end of the second wire wasn't connected to anything, so I fastened it to the terminal on the solonoid.
I didn't check the voltage of both wires, but I have a bulb type circuit tester. The wire that is fastened to the solonoid lights the bulb very bright when the key is in the start position. There is no power when the key is in the "on" position.
The wire that goes into the wiring haness has power when the key is in the "on" position, but the bulb in my tester is dim, which leads me to believe that it is a resistor wire, and the power has dropped.
I'll get a voltmeter and measure it tonight.

 

Checked it.
It's 9 volts to the coil when running.

 

They must have changed the wiring harness at some point between 69 and 73 then. The resistor wire goes to the starter solenoid and is wrapped in yellow high temp woven fabric insulation.
I confirmed that it was the resistor wire when I installed the new harness. I left it disconnected at both ends and ran a separate non-resistor wire in it's place because I have a Pertronix II ignition installed and it requires 12V at all times.

 

The yellow-striped wire does go to the starter solenoid and supplies 12 volts to the coil when the starter solenoid is energized with the ignition key. The red-striped wire goes to the firewall junction block and then directly to the ignition switch, supplying a reduced 9 volts to the coil after the key is released from the start position and left in the run position.

 

Your resistor wire may be discolored but appears to be working well. Mine is at 11 volts and went for a ride yesterday...still cutting out under load and probably trashing the new set of points and condensor. I really hate the thought of changing the resistor wire in the harness.

 

OK, I just looked again. The resistor wire on my 73 is actually black with pink printing. I disconnected the yellow wire from the starter as well because I didn't want those unused wires energized.

Neither of the wires have stripes.

 

The yellow wire from the starter solenoid is only activated during the START portion of the ignition sequence. After you release the key to the RUN position, power on that line is dropped and voltage only gets to the coil via the resistor wire. The starter solenoid wire is a direct 12vdc for easy starting only. You can remove it....and you may not notice a difference--until you experience cold weather, etc. There is no 'downside' to leaving the yellow line connected to the positive coil terminal...as long as it is wired as the factory intended.

 

Both the resistor wire (black with pink script) and the yellow wire from the starter solenoid are crimped together in the same terminal at the coil.
I have that disconnected from the coil because I need to have 12 volts to the ignition at all times. I removed the resistor wire's terminal from the fuse block and replaced it with a non-resistor wire that I ran to the coil.
I then had two bare terminals (one at the coil with both the yellow wire and the resistor wire attached, and the other end of the resistor wire at the fuse block) hanging free. If I left the yellow wire attached at the starter both of those bare terminals would be energized during start up. I didn't want to cut them off because it was a brand new wiring harness and I wanted it to be able to go back to the stock configuration if ever needed.
I could have simply taped up the bare terminals, but electrical tape doesn't always stay in place and it could leave black residue on the wires.
I opted to just disconnect the yellow wire at the starter and then I could simply tie wrap all of them out of the way. Simple, clean, safe, and completely reversible should I ever need to.

 

Roger
I searched the forum and found this thread with posts by you and 69427. Very informative. The OP should read and re-check his ignition primary circuit.

http://forums.corvetteforum.com/c3-t...re-issues.html

I checked my static voltages thru the resistor wire and found 5.87 volts with points closed and 12.01 volts with points open. Looks like my resistor wire is ok.

 

Your readings look correct. (May I also commend you for checking it the correct way if an oscilloscope is not available. ) The voltage(s) at the coil C+ terminal can only be measured accurately (if using a voltmeter) when the engine is not running. Actual running voltage measurements require an oscilloscope. (At zero RPM the coil's inductance, the part that does all the energy storage work, is invisible for all intents and purposes and the coil's winding resistance is all that's seen at the coil. The ballast resistor and the coil winding resistance will form a voltage divider powered by the 12v battery. This will produce the readings seen above. Once the engine starts, the coil's inductive reactance, essentially a time varying AC resistance, adds to the system resistance and gives inaccurate voltage readings if done with anything other than an oscilloscope.)