Bad electrical problem

[Bill L.]

Re: Bad electrical problem

Noel:

You may not want to hear this but if I had this issue I would also eliminate the Pertronix set up as well..... It may or may not be the culprit but strictly speaking it is a "foreign body" in the equation of trouble shooting......

Regards
Bill

[R N.]

Re: Bad electrical problem

Noel,

I too had a similar problem as many other have. My problem was a loose ignition coil in the mounting bracket. Bumps in the road caused the coil to turn slightly causing one of the coil terminals to ground to the ignition shield causing the engine to stop.

[Russ S.]

Re: Bad electrical problem

Keep the original switch as replacements don't work the same as originals.

We have checked the items listed in your responses but did not find any obvious trouble spots. The bulkhead connectors looked clean and seemed tight. Of course, we can't really tell if we are fixing anything because when we let the car run in the shop it never stops. Such is the dilemma with intermittent problems. My mechanic suggested changing the key switch so I have ordered one. Any other ideas - fusible link, fuse box, coil (I have Pertronix ignition)? I'd take it for a road test but don't want to get stuck in traffic again.

[Frank D.]

Re: Bad electrical problem

I had the dreaded 'red wire' symptom in my '63 and a busted retainer clip on the connector to boot. I wound up 'repinning' the entire connector; not for the faint of heart. Make sure that no pins are pushed in either; then I would make sure no part of my ignition shielding was pinching wires at the ignition coil or maybe even cutting them along the bottom rear edge; also take a good look at the ignition switch connector and wiring.
I put some of that chrome door edge guard along the bottom of my repro top center shielding to protect the wiring and put the original one on for judging.

[Noel B.]

Re: Bad electrical problem

Frank - I had already removed the ignition shielding before experiencing the multiple failures so I don't think that is it. However, I will double check the coil wires to be sure. What are you showing in the first picture? I don't understand this one. Thanks.

[Richard M.]

Re: Bad electrical problem

Noel, It may be the IGN switch, but rather than guessing....

Connect a digital voltmeter to the IGN wire(Pink/Black IIRC) on the back of the switch when you test drive it. When the car looses electrical power, test the IGN wire for voltage, then test the RED feed wire going to the switch.

If the IGN wire is no-volts, then test the RED feed. If you have RED feed volts and no IGN wire volts, it's the IGN switch. If no RED feed volts, it's back from there.

All of your symptoms lead me to believe it's the Bulkhead connector RED feed wire. Also keep in mind that the RED feed behind the fuse panel could be corroded. The fuse panel must be removed to check that. The above test will determine if you need to check behind the fuse panel. Ensure the battery is disconnected if you get need to get in there.

Rich

[Noel B.]

Re: Bad electrical problem

Excellent suggestions. I'll try these next week and hopefully I will be able to isolate the problem.

Since losing power suddenly can create an unsafe condition, I would obviously like to be sure that the problem is gone before driving the car on the road very much. Would it be possible for me to run a separate new red wire of sufficient gauge to create a parallel path for this circuit? That way I would bypass any trouble with corrosion in the bulkhead pins.

[Noel B.]

Re: Bad electrical problem

Regarding the jumper to bypass the connector I am planning to take a #12 red wire and feed it through the firewall. I'll connect one end to the red wire at the ignition switch and the other end to the red wire on the horn relay in the engine compartment. I think this will create a parallel path to provide power if the connector is bad. I downloaded a wiring diagram and this looks correct to me. Please confirm that this will work before I proceed.

[Richard M.]

Re: Bad electrical problem

Noel, Yes that will bypass the existing wire. However, I recommend you add a 30 AMP Fuse to your jumper wire at the IGN switch junction. This will prevent a catastrophic fault if the wire inadvertently falls and hits ground somewhere.

So, this will help isolate the fault, but if it does work repeatedly, you still won't know the exact point of failure of the original wiring/circuit.

If it does work, then it would lead me to believe your problem is in fact in the bulkhead connector or fuse panel areas.

Rich

[Gene M.]

Re: Bad electrical problem

Noel, It may be the IGN switch, but rather than guessing....

Connect a digital voltmeter to the IGN wire(Pink/Black IIRC) on the back of the switch when you test drive it. When the car looses electrical power, test the IGN wire for voltage, then test the RED feed wire going to the switch.

If the IGN wire is no-volts, then test the RED feed. If you have RED feed volts and no IGN wire volts, it's the IGN switch. If no RED feed volts, it's back from there.

All of your symptoms lead me to believe it's the Bulkhead connector RED feed wire. Also keep in mind that the RED feed behind the fuse panel could be corroded. The fuse panel must be removed to check that. The above test will determine if you need to check behind the fuse panel. Ensure the battery is disconnected if you get need to get in there.

Rich

Rich,
Excellent path to take, That heavy red wire sure can build up a lot of resistance going thru the firewall connector. I don't know how many times I uncovered a partial melted connector as a result of corrosion or the owner installing some "hot rod" ignition system. If lucky the clean up and replacing of the plastic connector housing yield a functional system once again. I always save old harnesses for future parts scavenging.

PS discard any bogus ignition system that is over loading the system. Pertronix points elimination should be ok but too many go bad for me to trust them.

[Noel B.]

Re: Bad electrical problem

My mechanic noticed that one of the wires to the solenoid looks kinda fried so he is going to replace the end of that wire first. This condition was mentioned in one of the previous posts. If that doesn't eliminate the problem we will proceed with the jumper to bypass the red wire. I'm inclined to do this anyway just to avoid further problems with the bulkhead connector.

Thanks to everyone for your help. This is a great forum! I'll let you know how all this turns out. The weather is nice in northern CA and I want my Vette on the road where it belongs.

[Richard M.]

Re: Bad electrical problem

Noel,

Here's a photo of the inside of the fuse panel(of a '66) for reference. You can see the Red wire coming in from the bulkhead connector(left block, upper right terminal), which comes from the horn relay buss bar, which is sourced from the battery lead at the Solenoid main feed.

You can also see where the Red wire feed goes into the fuse panel. It's spliced in the harness, and also goes to the IGN switch. Notice the blade terminals and the corrosion that happens within the panel itself. This is quite often overlooked as it is hidden.

If you decide to remove the panel at some point and do a visual of the panel internals, simply remove the harness tape from around the mating halves of the joint to allow access inside.

Rich

[Noel B.]

Re: Bad electrical problem

We may have located the electrical problem. We found that the wires at the solenoid were damaged by heat and spliced on some sections of new wire - per Charles Clifton's suggestion. My mechanic drove the Vette for about 15 miles (with a chase car...) and everything OK. I think I'll stay near home for a few weeks just in case. We inspected the bulkhead wires inside and out but didn't find anything that looked bad so the jumper wasn't installed.

Thanks again for all of your assistance. I am a lot more knowledgeable after reading all of your responses so I will be more competent if anything like this happens again (but I hope it doesn't).

[Noel B.]

Re: Bad electrical problem

The intermittent electrical problem came back after a couple months. Usually the clock would start running and everything would be operable in a few seconds or minutes so it was hard to troubleshoot. Finally, the car died on my street and the clock stayed stopped. I ran to my garage and grabbed the voltmeter. I found no power at the coil with the ignition switch in the on position. Then I tapped on the bulkhead connector and the power came back on.

The connectors looked too brittle to mess with so I decided to go with the bypass wire as suggested. I ran a #12 red wire from the horn relay through the firewall and connected it to the "bat" terminal on the fuse panel. The previous posts suggested to connect to the headlight switch but the "bat" terminal was much easier to get at. The wiring diagram indicates that this will do the same thing - am I correct?

Seems to be working so far...

As always thanks for your input.

[Richard M.]

Re: Bad electrical problem

Noel, I believe the original wire from the horn relay buss bar is a #10 not #12. Yes, tying it to the BAT terminal is a junction point, as you can see in the photo I posted of the backside of the panel. Since you're doing a non original type rewire, I would suggest that you install a suitable fusible link at the horn relay buss bar source connection. A #10 would require a #14 fusible link. You 'could' use a fuse, probably at least 30 amp, but that could be shy during crank.

One thing to keep in mind.....If those bulkhead pins have had heavy corrosion and have been compromised, this causes high heat in the insulation. If the compromised source wires heat enough it can cause adjacent wires to melt.

Just the other day I cut open a old 1966 engine harness. I still have it handly and will try to snap a photo. I found several melted wires, which by observation were stuck to and next to the Purple starter Crank wire. This wire is usually the high heat cause on those over cranking situations over time, expecially hot engines on hot days.

In your case, I would highly recommend a detailed and thorough check of your wiring system. It may be time for a complete rewire with new Main, Engine/Forward, and Rear harnesses.

Rich