[north]

Wondering if anyone has had the same problem as me…

Burned a set of points in only a few hundred miles. Second time it has happened. I tested the voltage to the coil + and I was getting full voltage (instead of the typical 7ish) while running. I even bypassed the ignition switch and same result.

All the wiring including the resistor wire looks nice and unmolested. Can a resistor wire go bad in a way that leaves it allowing full voltage?

[gtohurstjudge]

My 69 GTO's resistor wire did the same thing back in the 1980's. At the time
I fixed the problem by adding a Chrysler resistor block on the firewall. Later when i did
a frame off on the car around 1990 I installed a reproduction engine harness.....no issues since then.

[Kenth]

5-7 volts should be seen with ignition on points closed, about 11 volts engine running.
With boken or missing resistor the engine wont run.
Is the re resistor cable replaced with a non-resistor cable?

[johnta1]

Change the condenser in the distributor. it keeps the points from burning up too quickly.

Is the resistor wire under the dash?

I think the 69 didn't have the yellow wire from starter to distributor.
The ignition switch on column to the firewall has the yellow and black/pink connect at the inside firewall connector. So I would think the switch is 'bad' letting full voltage go the firewall at all times?
(if Kenth's suggestion checks out)

Could check the voltage of the black/pink wire under dash to see what the voltage is and/or see if the yellow wire has 12 volts in 'run' position. (it should not have 12 volts on 'run')

[north]

It’s a 69. The resistor wire is in the dash harness. It is a milky grey color and actually has resistor printed faintly along its length. It is all obviously original. I unplugged the ignition switch and sent 12 volts through the resistor wire and got full voltage at the coil.

I wonder if a resistor wire can fail by not resisting rather than simply cracking and not transmit any power? Perhaps somewhere near the ignition switch the yellow wire (non resistor cranking ignition supply) is making contact with the resistor wire and allowing full voltage to reach the engine harness wire to the coil?

I’m thinking I might take a resistor wire from another old dash harness.and temporarily connect it instead of the original and see if that does the trick.

[johnta1]

That should work.

When you take the wire out, see what it looks like under the insulation?

[locomotivebreath]

Just an FYI if ya have to , I went back to points on my 68 and used an AC Delco F1104 ballast resistor . Small ceramic block type that I mounted on the stock coil bracket . It has the correct 1.8 ohm and put out about 9-9.5 volts . Works great and it’s pretty well hidden by the air cleaner .

[RFCOLEMAN]

I had the same problem in a 69 GTO a few years ago. Burt up 2 sets of points in a few miles. Turned out it was the ignition switch. It was driving me crazy. After a lot of voltage testing, I found that the switch was still supplying 12 volts to the coil after the car started and switch was in the run position. Put a new ignition switch in, and problem solved. Just another possibility to check.

[johnta1]

Agree with that.
Also cannot believe a wire would become less resistance.

[north]

Thanks all, I did try a different ignition switch and tried adjusting it in case it was an issue of the yellow wire still transmitting voltage in the run position. My best guess is that the resistor and yellow wire are shorted somewhere.

[gtohurstjudge]

As I already stated, the resistor wire runs from the junction block on the firewall to the coil......there is NO resistor wire in the dash harness. There are only two possibilities........your car has an "R" wire on the solenoid and the solenoid is bad feeding
a constant 12 volts to the coil, or the resistor wire has gone bad, which is what was wrong with my GTO fifty years ago. I noticed that everybody ignored my first post, but if you want to know if I am qualified to give my opinion, I've owned my GTO for 54 years, and I was in the car repair business for 47 years, so you might want to consider my opinion on the matter. Yes, resistor wires can lose their ability to lower voltage, I've seen this problem several times both on my GTO and on my customer's cars.

[north]

Thank you, however as per the 1969 shop manual and the physical wiring in my car the resistor wire does run from the ignition switch to the connector block on the firewall behind the fuse box. I tested the ohms of that resistor wire (it is even printed its length as a resistor wire) and it meets spec at 1.5 ohms. I also physically inspected all the engine harness related connection at the junction box and all were clean, tight and in the proper location. I also ran continuity tests on all those wires. During the continuity tests I physically jostled the engine and dash harnesses for signs of fluctuation caused by cracks or bad connections but no issues appeared.


The dash harness is clearly factory and in excellent original condition and has never been modified or damaged in any way. The engine harness was replaced last year but all wires were again tested for location and continuity and all tests were normal. As I have other cars of the same model and year I ran some comparative tests and detected one anomaly.

If I measure the voltage (engine off, ignition at run) at the ignition switch on the yellow (cranking feed to coil) wire all the other cars they show 6-7 volts but the car in question shows twelve. The 6-7 volts in the run position makes sense because while the yellow wire is disconnected at the ignition switch when it is in run it and the resistor wire (run feed to coil) are joined together at the junction box where the both potentially supply the black - pink stripe wire to the coil +. So the yellow wire gets the reduced back flow voltage from the connected resistor wire.

The fact that I’m measuring 12 volts under this scenario (ignition key in run position measuring the yellow at the switch) on the problem car means that the coil feed circuit is incorrectly getting 12 volts from another source with the key in run but not in the off or acc position.

Any thoughts on what could be that source? Could a defective solenoid be the source at run but not in off or acc? The car starts fine and turns off normally with the ignition switch rotation. Also to eliminate other possibilities I replaced both the coil and ignition switch even though they both tested fine. Neither replacement made a difference.

["QUICK-SILVER"]

This yellow wire volt testing done with points open or points closed?

You wont see reduced voltage on the circuit until it has a load on it from points being closed.

Clay

[johnta1]

Possibly take the wire connector at the switch on the column, and check at the loom for voltage at each of the 2 positions for the 2 wires.
(hard to explain)

The 'yellow' wire post should only have 12 volts in 'Start'. (basically bypassing the switch) I guess you may have to jumper the power wire to it. then check the resistor wire for voltage.
(thinking out loud, haven't checked the schematic)

Need to see where the 12 volts is entering the resistor wire or the firewall connector. (inside and engine side)

[johnta1]

Here are pics of schematics:

The only place they 'meet' is at the firewall connector. Should be NO 12 volts at Yellow except in Start position.

Ignition Wire and Yellow


Part 2

[FrankieT/A]

As johnta1 said earlier the condenser is usually what causes the the points to burn prematurely. I f you feel the problem is the resistor wire and want a cheap easy fix, just use a resistor coil(coil that is internally resisted) and no one would be the wiser. Just my opinion...