1969 electrical problem

[Bob King]

Gentlemen - Last week while driving home from work in the rain at night in my 69 350/300 4speed with A/C, and Petronics 1, the car died several times. There were a couple of times I did not think I would make it home, but I did.

The next day I discovered that the Die Hard battery was dead and I got it recharged. Next I drove to Kragen and they tested the 1.5 year old Delco-Remy alternator and found that it was dead and upon removal of this alternator I discovered that the red wire going to the back of the alternator, with the rubber boot cover, was burned and hardened for the top 2 inches and the metal connectors were also scorched. Now with the new alternator and recharged battery I noticed that sometimes (not always) when I turned on the headlights with the idling engine the engine would die immediately. If the engine was around 1200 - 1500 rpm or more, it would not die. I noticed that with the engine at idle and when I had the defrost on and the fan blower switch at the second highest speed, the engine idled normally, but sometimes when I turned the blower fan to the highest speed the engine would die immediately. I believe the same thing happens (engine dies)when the windshield wipers were on. The car does not die when the radio and/or the inside/interior lights are on.

Today, I called the Petronic Tech Line and spoke to a very nice gentleman who said to test the voltage at the coil with the ignition switch turned on. I believe I did this voltage test properly tonight and got a reading off of the postive terminal of the coil of about 4.2 volts. The Petronics tech said I should get a minimum of 8 volts from the coil with the ignition turned on, for things to operate properly. The Petronic tech said to call him back tomorrow and if the voltage is below 8, he would help me further with some other procedures and that the resistor ignition wire running from the ignition switch to the coil may be bad and the problem. The Petronics said he thought I had a low voltage problem.

The LeMans blue Vette runs fine when the headlights, fan blower and/or the windshield wipers are not on. So, don't worry I will not be driving at night, or in the rain, or turn on the fan blower until this problem is fixed. I do not understand why a fuse or fuses did not blow, thereby saving the alternator.

Thank you for your help. I want to get this problem fixed as soon as possible, so I can keep driving this great car around town (and to work). Thanks. Bob King

[Jim T.]

Re: 1969 electrical problem

Why are you using the original resistor wire? Does the Petronics electronic ignition state that this should be used? I have a GM HEI distributor in my 70 and it has to have full 12 volts. I ran a wire from inside connected to the fuse block IGN terminal through the firewall and connected it to the HEI. Only time power is activated is when the ignition key is turned on.

[Joe R.]

Re: 1969 electrical problem

Bob,

Originally your battery went dead or partially dead and your alternator burned itself up trying to supply the correct voltage to your Vette.

NOW, the problem is in your electrical system again. The battery was probably not fully charged when installed and the alternator is probably trying to charge the battery and run the Vette at the same time. Won't happen at idle or RPM's below 1500 to 2000.

Get the battery fully charged and checked along with checking the alternator for output. Do that before driving it a long ways again. Also, check the wiring and make sure that it's not burned and giving you high resistance and therefore low voltage.

These things should fix your Vette like new again,

Regards,

JR

[Craig S.]

Re: 1969 electrical problem

Bob - Joe is right, and personally, I would bypass the ballast resistor and supply the full 12V to the pertronics amp.....Craig

[Bob King]

Re: 1969 electrical problem

Mr. Ray - Thank you for your response. Re-charging the battery and checking the alternator voltage is easy. But, which wire should I be checking? The 2 large red wires that attach to the alternator? Or the wires from the Petronics to the coil? I suspect you are referring to the 2 red wires to the alternator.

Thanks to everyone that responded to my question and problem. This is a great forum and a great way to fix my old car. Bob King

[Joe R.]

Re: 1969 electrical problem

Bob,

We've all seen a lot of problems with these old heaps. No need for the thanks, just helping out when we can, as someone else has learned the lessons the hard way and exchanged their knowledge with us.

Yeah, it's the red wires that sometimes can't carry the load after they get hot and oxidize.

Good luck,

JR

[John H.]

Re: 1969 electrical problem

Part of the problem is that your Pertronix module isn't getting a full 12 volts like it needs; when it's connected to the coil (+) terminal, that's only supplying 7-8 volts to begin with (assuming a full battery charge and a properly-functioning alternator). The Pertronix instructions are poorly written - where it says to leave the resistance wire or ballast resistor in place, that refers to powering the stock coil, which needs the reduced voltage, NOT powering the Pertronix module. The module (red wire) needs a full ignition-switched 12 volts, a stock coil needs resistance-reduced voltage, and aftermarket coils need whatever their manufacturer recommends (some are designed for reduced voltage, some aren't).

[Bob King]

Re: 1969 electrical problem

John, Ray, Craig and Jim - I finally got a chance to take the battery back to Sears again and they gave me a new one, which helped the situation, I think. Now I have a new battery and alternator. But while driving the car tonight a little bit, when I had the headlights on and the defrost fan blower on the highest speed and the engine died once; and another time when I turned the fan to the highest speed with the lights on, the engine stayed on at idle speed and did not die. It is a little bit cold out tonight, probably 45 degrees, and I do not have the choke operating on the Edelbrock carb. Maybe the engine died the one time because the engine was still cold, but I don't really think so. The engine was warm when I had the headlights and high speed fan on when the engine stayed at idling speed of 800 rpm, or so.

I just checked my Petronics connections and the black wire is smartly attached to the negative coil post and the red wire along with the black capacitor wire and the 2 cloth cover wires (yellowiish and whitish colored)(that come together on the same metal connector) are nicely attached to the positive coil post.

I wonder which colored wire goes to the ignition switch, the yellow one or the white one? I think the yellow one goes to the starter solenoid, because I got under the car last night and checked the starter connections to make sure they were tight. I think I saw a yellowish colored wire connecting to the solenoid.

Ysterday, I talked to Carl, the tech at Petronics, and he was saying that he hears alot of times/cases where the resistor wire, that goes from the positive coil to the ignition switch under the dash, is bad; thereby not allowing full connection and volts to the system.

I promise that I'm not trying to buy trouble and really don't want to have dig in under the dash, lower the steering column and all of that (because I know it's difficult) unless I know that will solve the problem, if I have a problem.

So with this info, do you have any further thoughts? Thank you. Bob King

[John H.]

Re: 1969 electrical problem

Bob -

Your (stock) wire connections to the coil are correct - the cloth-covered white [resistance] wire goes to the ignition switch, and the yellowish one goes to the starter solenoid (to supply full 12V when cranking). The problem is the Pertronix red wire - it needs to come off the coil (+) terminal [where it's getting reduced voltage, maybe less than that if the resistance wire is going south] and get connected to an ignition-switched full 12V source.

[Chas Henderson #28127]

Re: 1969 electrical problem

Bob,
Have you thought about dumping the printronix set up and putting the points back in to see if that is the problem? I did have the printronix set up and it worked fine for me in my sb 71. I put points back in to get top flight, and that was three years ago. My lights would dim and the turn signal would slow up, so I upper the idle and that helped. Mine never died, and never gave me any other problems and I drive it alot to work and around town, not just to shows. If it still gives you problems, then you can try another approach.

Chasman

[Bob King]

Re: 1969 electrical problem

John - Thank you for your suggestion of taking the red Petronics wire off the coil, which I did. I connected this red wire to a black wire that had been previously cut(not by me) that goes to the windshield wiper spray pump. All accessories seem to run correctly now, however, when starting the car now , it starts but you do not hear it fire up until the starter switch is released. So This new black wire with the Petronics red wire connection is probably not an ignition switched wire.

Where can I find an ignition switched 12 volt wire? Can I find an ignition switched 12v wire somewhere around the firewall, near the distributor?

Evidently my resistance wire is not letting enough current through and may some day need to be replaced? Is that correct? Is that a difficult and big job? Can you describe what needs to be done to replace the resistance wire and is it something I should even consider doing?

Thank you. Bob King

[Jim T.]

Re: 1969 electrical problem

Bob what I did to provide 12 volts to a HEI distributor that I put in my 70 was real easy.
Inside the drivers side where your fuse panel is there should be in the center of this panel a electrical spade connection marked IGN. Make up a wire to connect to this spade and thread it through an established hole in the firewall. This wire will only have voltage when your ignition is on and will work just fine.

[Jim T.]

Addendum

Your original cloth covered ignition resistor wire is designed to reduce voltage so the original factory points would last longer. Recommend that you just tape up the exposed electical end to protect it. You may someday go back to the points, hopefully not because you are stranded on some interstate because the Pertronics failed.