I just got a new '72 coupe BB, its rebuilt mostly standard, slight changes (electric fan)
It was trucked from NC to California then shipped out to me over 2 months, so had a good level of grim on it.
Also the shippers left the battery switch on which has flattered the battery as it would appear the door switch for the interior lights doesn't turn them off.
So nothing unexpected, (fired up as soon as she got fuel into the bowls, possible miss on 1 cylinder) however on starting her up with jumper cables initially everything seem to function correctly except the fuel and temp gauges didn't move, these did function when purchased.
Alternator was charging a still very flat battery at 13.5V.

After a while of inspecting the car (lots of on and off, had to restart on jumper cables each time) I noted a number of other intermittent issues,
Indicator stayed on solid (not flashing) for about 30sec then went back to normal operation.
Starter began to struggle to turn the motor over - though possibly the 2nd battery was just going flat

Then after running for 5mins (only on flat in car battery) all the electrics started to shut down, headlights, dash & interior lights dimmed, and then went out, I assume the alternator was still working as the car kept running.

Makes me think there is a massive short in the system, though didn't smell, see or hear anything.

I ran out of daylight, have left disconnected battery to charge over night, if its still flat in the morning ill replace it.

So asking knowledgeable members where would you start looking?

 

I'm thinking check fuses for water/dirt and inspect for damage to wiring looms, after which i'll stick Volt meters on different parts of the circuit and see whats happening.

 

Charge a battery and install it. The other option would be to purchase a new (charged) battery.

 

THEN...put a voltmeter across the battery. If its around 14 v running, your charging system, alternator is OK.

If gauges or whatever are still bad check fuses!!!

Some batteries never recover after being severely discharged. Don't make this more complicated than what it could be if all was OK before!

 

Good news: The C3's don't have high technology electrical systems. Bad news: Notwithstanding they can have enigmatic electrical problems..compounded by their fiberglass body.

A comment: I wouldn't recommend trouble shooting an electrical problem with the battery connected. The battery can pump out 600+ amps into a short circuit, destroying components...and worse burning the wire harness.

I've done this on my 68 after making extensive electrical changes. I started out with a AA dry cell battery pack delivering 12 volts. Not enough voltage to destroy anything. I verified no problems with just 12 volts on the 68 power bus. Next I used a 12 volt power supply that had enough current capacity to operate the headlights. I similarly checked out the cars electrical system and switches that could operate the lights. At this point, I powered up the car with the battery......Sure a few bucks for the 12 volt AA battery pack, and about 80 bucks for the 12 volt power supply....but I didn't burn anything up, and also with such low energy levels I could work comfortably looking for unusual power drains.

For working on electrical problems, you really have to get a color schematic that shows photos of the electrical connectors, wire colors etc from Dr Rebuild. It'll cost about $30.00. Also, I don't know if still available, but on Corvetteforum at one time you could buy some nice color coded schematics from Dale Olsen engineering. For my electrical work on my 68 and 70, I use both the Dr Rebuild and Olsen engineering schematics side by side. I've found the GM black and white schematics in their shop manuals to be hopeless.

Good Luck!! Working with a C3 in New Zealand is really challenging!!! Been to New Zealand three times. Once, a tourist package bus trip to the South Island and another a self sponsored tour with a rental car visit to the North Island and the Bay of Islands.

 

Thanks guys.
Charged battery and all the random issues went away. But still no fuel or temp Gauge movement.

Got a bit destracted today and ended up giving her a better clean and wax, fixed door switch And installed a few things i need to get her on th road here in NZ, wing mirror, Sunvisors. (still need to install a high brake light, wiper washers and brake balance) joys of getting an old car on th road here.

Will have a go at electrics tomorrow.

Yeah Definite tougher getting parts down here in NZ.

 

same here in Australia,
on here they say if it's broken etc, just go get a new part
we just karnt run down the local parts place and ask for a replacement "XYZ" for a '72 vette,
they will just look at you strange.
there's only a handful of US parts places here, and they charge a hefty premium,
at least 3 to 4 times the price you pay over there.
and there's the shipping charges, then waiting for weeks n weeks sometimes for them to show up.

if a big vendor from the US opened a store downunder, they would make a killing....

 

Hint hint, wink wink, nudge nudge, say no more...

 

It does amaze me that I can walk into a store in US and find stuff on the shelf. What helps is commonality with other GM cars.

I have gotten C3 radiators/condensers/AC parts same day

 

Hi Vandros in case you didn't already know we have a Corvette parts vendor in NZ based in Tauranga. He keeps a good selection of parts and is very knowledgeable.

 

Yip I've brought a few things off Colin in Tauranga, but also trying to keep the budget under control.

Got gauges working, all it took was a bit of sun to dry the car out i think.

Installed my wiper washers, man that wiper covering flap is a pain to get on an off. However i plugged the pump wires in which were disconnected but it didn't go. Will have to read up on the circuit and mechanism.


Started on the high brake light, having to pull the carpet up on a nice new install is a bit guttering, especially seeing I'll remove the light once its certified. Also am i correct in that the brake lights are also the indicators? (so the high brake light i'm installing will flash when i'm indicating)

 

I installed the high brake light and yes it does flash with the indicator

Could someone confirm my understanding of the below, yellow is always 12V when ignition is on and when the washer switch is pressed the dark blue wire between 17 and 5 is grounded?





Thus if a put a multimeter across the disconnected 14 & 5 and press the washer button i should get 12V?

 

the answer to the above is yes.

 

On my '68 I found that there were corroded terminals in the two "halves" of the fuse box/panel.....when I unbolted the assembly from the firewall and separated it, several terminals were coated with green oxide allowing only 5 or 6 volts to reach components in the engine by or in the dash.

 

Thanks Doorgunner

I pulled it all apart and got it figured out. Seems to be working once i cleaned it up and got it loose. But then found i was missing the cam inside.