Something Fried?

[Richard M.]

Re: Something Fried?

John,

That lug is definitely grounded. It doesn't belong there. You had a direct short from the ACC Brown wire to Ground. This short passed through the ignition switch to the 12G Red wire which feeds the switch. This 12G Red wire comes from the bulkhead connector which eventually comes from the buss bar on the horn relay, through a rubber plug-in connector, and is tied to a 10G Red which comes from the BAT terminal on the starter solenoid. There is no fusible link tied to the battery located at the solenoid post. I believe the "fusible link" is the 16G Black wire with a small rubber plug connector at the horn relay. It connects the 12G Red from the IGN switch to the 10G Red from the Battery post at the solenoid. I never had one of those go bad but that's the suspect in my opinion.

Here are some photos of the items in question from a old '67 Forward harness I had on the shelf. I added some arrows and text to describe.

P6160250.jpg P6160251.jpg P6160252.jpg P6160253.jpg

So.....You cannot test the fusible links or circuits without a meter, or without a test light if the circuit is powered. For now, do UN-powered tests with a meter. A link is a finer wire than it's load wire, inside the rubber, and will melt if blown, and it may or may not show external evidence of failure. So your visible checks of the links near the alternator/regulator are not accurate and could still be a problem, along with the one near the horn relay. You must test them with a instrument mentioned above.

The other possibility is you've damaged the ignition switch. Again, a meter or test light at the various source and destination points in these circuits is the best way to diagnose the fault and find root cause of the failure. You should have 12 volts on the 12G Red at the IGN switch at all times. If not, the fusible link at the horn relay buss bar is likely blown.

Curiously, what does that Radio Capacitor wire end look like? Is there and male terminal on it's end? That's where the Brown wire connector should connect.

Rich

[Richard M.]

Re: Something Fried?

Here's a few close up shots of the 16G fusible link/connector at the buss bar. This may be the culprit. As you can see, this one has been heated up over the years. It's original.

P6160254.jpg P6160255.jpg P6160256.jpg

[John G.]

Re: Something Fried?

Rich,
Your set-up at the horn relay is little different than mine in that I don't have the plug-in set-up that your harness has - it does have the cylinder indicating a fusible link. The insulation on it felt sticky. I could scrape it off with my thumb nail and found it was burned though. If that gets power from the battery why does the horn (and only the horn) still work? Seems like it should be the red wire? John

[Richard M.]

Re: Something Fried?

This harness came from a early (Nov '66 built) '67. As far as I know the harness is the same throughout production. It's possible that your harness had a problem once, and the 16G plug type link was replaced with a different link. Your fusible link there is probably blown. This makes sense that nothing works......except the horn.

The horn still works, because the feed from the battery goes directly to the buss bar of the relay first before it takes off through that link then to the bulkhead connector, then ultimately inside to the IGN switch.

That buss bar also feeds the internal relay coil inside the horn relay. It also provides power to the horn relay contact point at all times. When you push the horn button, it completes the relay coil circuit, closing the relay contact points with 12 volts supplied from the buss bar. This activates the relay, sending 12 volts via the terminal on the relay(Dark Green wire going to the horns), to energize the horns.

Here's a portion of the wiring diagram showing the circuit. Note the original wiring diagrams had a serious error. They showed a direct short between power and ground on the buss bar. I fixed it in the modified version with the text. I know someone who followed the diagram, and unfortunatly fried his harness. This was on a pre-1967 Stingray, which didn't have fusible links.

Corrected
Diagram_Mod.jpg

Original - Note the 12B(-) wire shown connected directly to the 10R(+) wire
Diagram.jpg

[John G.]

Re: Something Fried?

Thanks Rich, All your information has been really helpful. Does anyone make a replacement link? I guess I could just solder in a section of 16 gauge - at least to see if everything runs.

[Richard M.]

Re: Something Fried?

John, If that's it. I've got a good notion that it is, but we haven't proven it yet. Before you go further, do you have a test-light? I'd like to see you verify it's bad.

If it is bad, you can get replacement Fusible Links from Napa or other auto parts stores.

Here's the Napa part....
http://www.napaonline.com/Catalog/Ca...691_0452798066

and other sizes....
http://www.napaonline.com/Catalog/Re...Dp%3d3%26N%3d0


You can get a test light there too.

Rich

[Peter M.]

Re: Something Fried?

Hi John,You are getting fantastic help from Rich. He is always lending someone a hand. For what it is worth IIRC, fusible link should be 4 gauge sizes smaller than the wire you are protecting. 14 gauge fusible link would protect 10 gauge wire, 16 gauge fusible link would protect 12 gauge wire etc.Regards

[John G.]

Re: Something Fried?

Hi Rich. The link on the black wire at the horn relay is clearly burnt in half - no need to put an ohm meter across it. There may be other problems too but that link definitely needs to be replaced (I'll give NAPA a call tomorrow). Any tips on soldering in the new link? I will use an ohm meter on the other segments tomorrow too. Thanks again - John

[John G.]

Re: Something Fried?

Thanks for mentioning it Dave - I didn't think about the oil pressure line. I have wondered what else got hot and potentially damaged. John

[Richard M.]

Re: Something Fried?

Hi Rich. The link on the black wire at the horn relay is clearly burnt in half - no need to put an ohm meter across it. There may be other problems too but that link definitely needs to be replaced (I'll give NAPA a call tomorrow). Any tips on soldering in the new link? I will use an ohm meter on the other segments tomorrow too. Thanks again - John

GREAT!!! You found it!!! Okay, now to fix it. This presents another problem. I think whatever you do to fix it, will be a light deduct in judging because you're missing the original type 16G plug link.

So, a few options......

1- You can get that Napa link with the terminal end to attach to the buss bar. The other end needs a good solid connection. Soldering is best. Also stop by a local Radio Shack, or Napa may have this also......Heat Shrink tubing. Slip some over the wire before soldering it together. I usually use two. I get one on the joint, shrink it while the other is covered up so it won't shrink, then slip the second one over the first and shrink that one.

2- Try to locate a reproduction 16G link like original and do the same soldering and heat shrink method above where connected to the 12G Red wire inside the harness. Lectric Limited or M & H may have them. I'll poke around to see if I can find something online too.

Glad you found it!
Rich

[Richard M.]

Re: Something Fried?

Hi John,You are getting fantastic help from Rich. He is always lending someone a hand. For what it is worth IIRC, fusible link should be 4 gauge sizes smaller than the wire you are protecting. 14 gauge fusible link would protect 10 gauge wire, 16 gauge fusible link would protect 12 gauge wire etc.Regards

Peter, Yes I incorrectly said 2 sizes in my earlier post. You're correct, it's 4 gauge sizes smaller. Thanks for catching that.

Rich

[Richard M.]

Re: Something Fried?

Dave,

Yes the ground path always sees identical current in a short circuit situation. The cluster ground is a 12G wire. It's also grounded to the engine via the oil line, but also via the tachometer cable and speedometer cables.

And in this case because the fuse is in the path, i.e. the 16G fusible link, and that it did it's job to protect the circuit wiring, I'm certain that the other wiring has not been compromised. If no circuit protection is involved, all bets are off and anything in the path should be carefully scrutinized, including the ground wires embedded in the harness.

Thankfully the 1967 and later Corvette wiring has much protection. Pre '67 is always at risk. This is why I always add some fuse circuits in my C1/C2 restoration/repair work.

Rich

[Richard M.]

Re: Something Fried?

Wiring a Windshield Washer PumpIt all started when I took my '72 in for State inspection. I got some static about the washers not squirting. I've had the car for 30 years and they never squirted. When you pushed the switch...you could hear it hum, but no squirt...I figured the internals were gone so I decided to install a new pump. The fact that there was a "Mickey Mouse" aftermarket pump there always was a minor source of irritation anyway. Why on earth anyone would install this pump in the first place still baffles me...the pump was attached to the firewall and they had to buy and install a plate where the original pump was and put in a bunch of weird looking hoses. This had to be done prior to 1985 when you could walk into any Chevrolet dealer and buy the correct part off the shelf. Anyway, I get a replica correct pump, put in the correct hoses, connect the wires...it doesn't work...no hum. I'm wondering if I connected the wires wrong. Everything else on the car works fine...no problems. I was thinking of reversing the wires...but after reading John Golen's thread...I chickened out. My question is...if I reverse the wires, can I hurt something? I've gotten a lot of good advice from you guys in the past...so thanks in advance...Dan DiCio

Dan, Without really knowing the specs of your washer pump, and I'm not to familiar with the C3 setup, it's difficult to suggest the exact result if you reversed polarity.

You may want to start a new thread with the exact question so the C3 folks can jump in.

Rich
p.s. My gut feel, is that if it's just a small DC motor, reversing the polarity will just make the pump run backwards. But if it doesn't even hum at this time with the replacement, I'd say it's time for a test-light or test meter to diagnose the fault. It could be a bad switch or a open circuit in the wiring somewhere.

[Tim G.]

Re: Something Fried?

I've been following this topic, wow, you guys are good. I'm reading for future reference.

[William C.]

Re: Something Fried?

I addition it has a special high temperature insulation to contain the "thermal event" when it blows. Not just any type of wire with a generic covering will do...