My starter is finally gave out on my 77 so I ordered a new starter. while I was under the car disconnecting cables, I saw a red wire with fusible link that is badly damaged. This wire is connected withbig starter wire. I’ve looked at Haynes manual and there’s nothing written for the red wire. There’s 2 gauge wire and I know that is the main constant power wire. Could this red wire with fusible link be feeding another power source?

 

I copied this from the 1977 wiring diagram.

 

Your first mistake, a Haynes manual.
second, there are 2 forms of 1977 Corvette wiring, early and late. Late 77 will have 2 power wires with fusible links connected with the large battery cable. Early has one.

 

Your car is nearly 50 years old now. How is it that your just noticing this now? I can post up the power distribution chart from the Genuine GM Electrical Trouble Shooting Manual if you would like. Would be great to know if you have early or late wiring. Do you have a alarm switch in the drivers front fender? Or in the door?

 

I am not sure if I have early or late. There’s only 3 wires going to the solenoid. Big wire ( I suppose this is constant 12 volt) and fusible link wire to the left terminal of solenoid and one wire to the right (ignition). I read a post some where on this forum, thin red wire with fusible link connected to the left of the terminal is for the horn. I just bought this car few weeks ago for a project for winter.

 

Sounds like a early 77 to me...
To be sure, check your VIN number 00001-27372 you have a early build...
Anything after is a late build...
A early build 77 wiring I find to be an oddball, the engine harness connects to the forward lamp harness via aa TAP connector (normally under the brake master cylinder area)
This completes the charge circuit (one big happy loop)
The fusible link gauge size at the starter is 14 gauge, there is another fusible link at the bulkhead connector and that is a 16 gauge.
Hope you don't find the bulkhead fusible link needs replacing it requires a series 59 delphi/packard male terminal...
Worst design ever!

 

On my 1968 year car the larger red wire is the main connection from the battery to crank the starter motor. The smaller red wire with the fusible link is the power connection to the rest of the car. The horn relay connector acts as a distribution strip and connects to many other locations including the alternator which allows the charging of the battery when running. Not uncommon to have that link damaged from past overcurrent issues. Can be replaced with a new link or a modern fuse holder and fuse. I would suggest getting one of those large laminated color wiring diagrams for your year car.

 

I really, really think you need to purchase some gen.GM manuals for your 77. Nothing at the starter solenoid has anything to do with the horn.
I'll take some pictures of the power distribution from real GM manuals for you. Just give me a couple minutes.

 

OK, Power distribution, early 77. The one with the alarm switch in the fender.

As you can see, main battery cable and one fusible link wire to large post of starter solenoid. And those tap connectors mentioned above that are indeed under the master cylinder.
Next, late 77, the one that has the alarm switch built into the door lock.


Here we can see main battery cable and two fusible linked wires connected to the large post on the solenoid.
Not shown on a power distribution schematic, is the wire going to the small terminal, generally purple, it's the solenoid start signal wire. The wire from the switch that engages the solenoid. And that's it.

 

Just to be complete. A picture of the starter circuit.

Note the purple wire that goes to the small terminal on the starter solenoid.

And this switch on the drivers fender behind the front wheel and above the vent. This is the alarm switch on the early 77 cars.

 

I agree with ditching (burning!) the Haynes Shop manual and ordering a set of the genuine Factory Service Manuals. They are available on RockAuto.com for a very reasonable price on a DVD. Rockauto has several different manuals on their website for the various year models. I use only the FSM set and I have had less issues as they have better schematics and trouble shooting charts. I have two sets for each of my 2 Corvettes allowing one copy to be used and the other stays inside and clean where it is used to study the systems you are working on.

DocRebuild.com has the large format laminated wiring "charts", they are not quite a schematic but they do help when wiring the car or trying to understand the wiring that is in the car. DocRebuild has a bunch of other quality parts that he alone sells. His parts are of the best quality and I buy only his Vacuum Hose kits because they are the best out there. He also sells a laminated chart that shows the electrical connector ends which makes identifying parts much easier if you are not familiar with them.

The battery wire goes from the battery Positive (12Vdc) terminal to the starter 12 volt post on the starter solenoid. The little red wire with the Fusible Link sends power to the inside of the Corvette. The Fusible Link is the Corvettes "Last Line of Defense" in protecting your Corvette from burning to the ground. It is a vital piece of the wiring and needs to be replaced. Unlike others. I will only replace a fusible link with another fusible link (of the same rating) properly soldered into the wiring and covered with heat shrink. GM could have used fuses but they specifically chose to use the fusible links here and so will I.

Not knowing anything about a 1977 Corvette but on my 1968 BB the wire from the fusible link goes to supply power at the horn relay terminal strip. From here it goes into the dashboard and powers pretty much all the accessories inside the car. If the Fusible link on the red wire is burnt "open" and has no continuity going thru it then it needs to be replaced. This likely means that your C3 has had a major electrical short which was stopped only by the fusible link getting toasted. I would look around and see if there are any tell-tail signs of a bad short having occurred leaving any marks. I would do this to be sure that the short was repaired correctly and ensure that it was fixed for good.

Fusible links are readily available at NAPA stores as well as even on Amazon. I keep a spare set on hand in my garage. I had a Electronic Cooling Fan controller that shorted out and sent smoke out of the box and burnt my fusible links. On my 1968 I have 2 of them on my C3 and they are different sizes.

Many people like to upgrade their alternator, and when they do so the output power of the (higher output) alternator should go directly to the starter solenoid's battery positive post. This allows the alternator to have a straight shot to the battery with the larger cable. Now the power is going to the car's interior goes thru the fusible link and into the fuse box and powering the car.

Best regards,
Chris

 

Thanks for the write and also than 4 vette for the diagram. Good thing is fusible link is not burnt or I see any signs of short on the fusible link, the wire part before the fusible link is bent and insulator has been cut along with few copper lines. Regardless, I will be changing the link for safety. Thank you all. Yes, Haynes manual sucks!

 

I have late build… 421395. You are correct, I just disconnected the fusible link and it indeed have 14 gauge stamp. Thank you so much.

 

Then you should have 2 fusible links at the starter.
Here is a photo of my late build 77 fusible links...