Bad electrical problem

[Lawrence S.]

Re: Bad electrical problem

Noel,
It sounds like your wiring harness is a mess with brittle wires and splices. Installing a new wiring harness on a C2 is simple. I almost every time I buy a "new" old car install at least one new wiring harness if the original is there or if someone has hacked up the harness. You can spend a lot of time chasing bad connections in these cars. Do yourself a favor and install new harnesses from the firewall forward. I use Lectric Limited but there are others out there. Just make sure you buy an OEM repro for your car.

Lawrence

[Ralph E.]

Re: Bad electrical problem

Noel, sound to me like the ignition shield is grounding out the ignition.
Try removing the ignition shielding at the distributor. If the problem goes away you've found the issue. Probably the coil wire is contacting the shielding.
Just my $.02

[Lawrence S.]

Re: Bad electrical problem

That is actually a good call. I have had that happen to me.

[Noel B.]

Re: Bad electrical problem

I did install a 30 amp fuse in the bypass wire so I should be protected.

Regarding the ignition shielding, I removed it during the summer when I converted the Pertronix back to points. I decided not to reinstall the shielding for the time being to avoid any issues with the coil wires. I can put it back on when I go to a car show.

[Harry S.]

Re: Bad electrical problem

There have been many good suggestions in this thread. Please remember that a GM harness was designed to last 15 years. As others have said if you think it is more than 15 years old, replace it. Go back to stock (distributor, coil, etc)

Good Luck

[William F.]

Re: Bad electrical problem

If you run a #12 wire from bottom connection on headlight relay on driver's kick panel to horn relay , do you need to fuse this "extra protection" wire?

[Leif A.]

Re: Bad electrical problem

William,
I most certainly would.

[Noel B.]

Re: Bad electrical problem

I installed a 30 amp fuse in the #12 wire from the horn relay to the bat terminal on the fuse panel.

[William F.]

Re: Bad electrical problem

A few electrical questions:
Is suggestion that I fuse the jumper wire I'm thinking of installing from headlight motor relay to horn relay because the factory "red wire" is fused at fuse panel?
Wiring diagram in service manual shows only one red wire attached to horn relay. Mine, '67 with AC, has 2 red wires attached to horn relay: one coming out of wrapped wiring harness close to horn relay, the second one has a 30 amp fuse in it close to where it attaches to other connection on horn relay and runs outside of bigger wiring harness until it enters a wrapped part of wiring on front of firewall behind ignition shielding. Is this original? What is it for?
Thanks

[Peter M.]

Re: Bad electrical problem

Hi Bill,
The second red wire at the horn relay is part of the AC harness, it provides power to the blower motor relay for high fan speed. It should have a 30 amp fuse. Check the AC section of the service manual for the AC wiring diagram.
If I understand the first part of your question correctly the "red wire" is protected by a fusible link at the horn relay, it is not fused when it comes through the firewall, a branch of that wire does go to the fuse panel and through a fuse for power to other circuits. For your jumper, do you mean the headlight motor circuit breaker? I would protect the jumper with fusible link.
For what its worth I am not a fan of jumper wires, there are probably other issues that will start to show up.
Maybe Rich Mozzetta will comment, he has forgotten more than I will ever know.
Kind Regards,
Pete

[William F.]

Re: Bad electrical problem

Thanks Peter,
I'm talking about a jumper wire from bottom lug on headlight electrical part on driver's side kick panel to positive lug on horn relay to give insurance if firewall connectors get bad and everything shuts off while driving. I've had this happen at night , very sphincter tightening. Thank God it was intermittent. I cleaned terminals at connectors and working fine now, but would like to have jumper for "insurance." Suppose you'd still recommend 30 amp fuse or fuseable link in this jumper? Does Richard M also agree?
Thanks again

[Peter M.]

Re: Bad electrical problem

Bill,
You need some kind of protection or bad things can happen. My preference would be fusible link.
By all means ask Rich for his opinion.
Kind Regards,
Pete

[Richard M.]

Re: Bad electrical problem

Gents, For the record I have to suggest new harnesses to guarantee proper electrical connections for safety. Or at least a proper repair of the Bulkhead Twinlock pins or terminals/fuse clips. But I understand on occasion it's not "preferred". So with that, I will try to help you do your modifications with safety in mind. Please ensure that there are no serious issues with ANY of the exposed wires in the harness. If you suspect issues inside the harness, it's time to replace.

First a review of the power paths. This applies to 1967. Similarly it will apply to earlier years except they did not use fusible links. I modified a few pages from the 1967 wiring diagrams from my AIM with colors and notations relative to the power paths. Crude, but it may help. You can download them to print or for a better view, or type CTRL+ in your browser to magnify.(CTRL0 (zero)resets to default).

REVIEW OF POWER PATHS
Power for the entire car is a #10G Red wire via a #14G FL(Fusible Link) at the starter Battery Cable connection at the solenoid lug. This #10G Red wire is spliced in the harness and routed TO the horn relay buss bar, the alternator, and the voltage regulator.

From the horn relay buss bar is a #12G wire via a #16G FL to be used as a main feed for the electrical system and this passes to the bulkhead connector, then into the main harness via splices to the Fuse panel, Ignition switch, Headlight switch, and Headlight Motor 40 Amp Circuit Breaker. Note this is above the left kick panel. The above wire at the horn relay buss bar includes a Fusible Link. On some cars, this FL may be a #16G Black wire with a round plug connected to the harness Red wire with a single spade terminal, as depicted in the AIM wiring diagrams. It is believed that there was a change made to the harnesses and this removable/replaceable FL was changed to a different configuration. It may be a fixed/sealed Black rubber tubular junction with a different color link wire, likely Orange #16G.
























ADDING NEW #12G RED SOURCE WIRE
If you add another #12G Red wire it is now parallel with the existing wire. Now you have 2 #12G wires feeding the same circuits. I highly recommend that you remove the original stock #12G Red wire terminal(via fusible link) from the buss bar and insulate that terminal thoroughly and tie it safely away from any potential short to ground or other harm.

Add a fusible link(#16G link) to this new additional #12G wire and connect at the horn relay buss bar terminal where the original was connected. Do NOT add the fusible link to this new wire at the interior of the cabin as the wire from the buss bar to the cabin is then unprotected. Additionally, if a fusible link blows inside the cabin, the wire burns and insulation expands and heats up and will smoke. Fusible links are always recommended outside the cabin. Route this new wire through the firewall at a new location. You can use the hole for the Wiper Harness/oil line Grommet or if not used, the hole for the 3-Speed equipped Speedometer Cable near the brake master cylinder. There is a plastic plug at this location. Whatever your path, ensure it is free from rubbing anything and insulate and tiewrap where needed.

The end of this new #12 Red wire "could" be tied to the Headlight Motor 40 Amp circuit breaker to complete the power source circuit, but I do not recommend this. FYI, he circuit breaker has a BAT stud, the Shorter stud, which is its input and is the junction/splice point from the #12G Red source wiring, if you choose to use that tie point.

It can be joined into the circuit via the Power Windows terminals on the fuse panel lower right of the panel. I recommend this tie point. These 2 terminals are also a junction/splice point from the source wiring. Use a female spade terminal securely insulated and positioned and tiewrapped so it won't move.

Whatever you choose, please choose wisely.

Rich
PS - For those owners with pre-1967 cars, you could follow the 1967 wiring upgrade to fusible links for added electrical system safety. Fusible links should be selected based on source wire gauge size "plus" 4....(technically, the FL number is larger but the diameter is smaller.) Eg #10G wire uses #14G FL, #12G wire uses #16G FL, etc. Always install in the engine bay/exterior and not inside the cabin. Always install at the source of junction current to protect the load wires and ancillaries downstream.

[William F.]

Re: Bad electrical problem

Thanks, Richard. Definitely not arguing, but why disconnect the factory red wire if you run a "jumper" in parallel to supply power in case the connector in the firewall box fails and everything shuts off-as I've had happen on one occasion? Too much load if both wires are running? I need a refresher in what happens with 2 12V wires are running in parallel as would be case if original red wire and added red wire are in place at some time. (double the amps,etc.? or not??)
thanks again.

[Dan D.]

Re: Bad electrical problem

You double (or half) cross sectional area every 3 wire sizes. So if you have 12ga wire and you parallel it with another 12ga wire you have essentially a 9ga wire. And twice the current carrying capacity.

-Dan-