Jim__H

Hi guys,
I'm now replacing the dash, console, and all of the wiring that I had to disconnect when I took it all apart a couple of years ago. Car is an early '77, build date Sept 1976, and this is the wiring diagram/schematic that I am using:

https://sites.google.com/a/c3vrmail....iring-diagrams

In the diagram it shows several terminal blocks some with numbered connections, my question is where are these located? It looks like they (or it) is sandwiched between the fuse box and firewall. If true, how does one access it? Putting the wiring back together that I took apart is not a problem but I also need to chase down a number of gremlins that were occurring in the short time that I drove the car before taking it down for a restomod. Like all four turn signals and the two indicators coming on when I turn the key, an intermittent problem that did not always happen. Probably a short somewhere but without access to those terminal connections it makes tracing the wiring paths.difficult. Unless I am missing something obvious which is always possible. Please enlighten me...

Jim

bmotojoe

Do yourself a favor and download Mr. Willcox 1977 drawing. It's a good drawing for an early build 77. If you're talking about the numbers inside the cells of the connectors, or bulkhead they are the actual circuit number. Right click lower drawing, save image as.....

http://repairs.willcoxcorvette.com/1...cer-schematic/

Jim__H

I have that one too, problem is I can't print it out in any size larger than 8 1/2 x 11 to take out into the garage with me. I suppose I should take the file over to Office Max and have them print it out.

I just fixed the parking light/turn signal problem and a couple of other loose ends so for now I'm good...

Shark Racer

FWIW, lectric limited sells some good blown-up wiring charts, 26x20.

0Willcox Corvette

Don''t print it out.... open your paint program and paste it in there... then save it to your desktop. Once you do this you can open it in paint and trace out circuits... For instance say you have have a headlamp issue, you can trace out all the wires and then re-save it on your desktop under another name so you can go back and review it later if needed. We used these in our shop almost every day. Once you isolate the circuit then you can chop out what you don't need, bring the schematic together and then print out a simplified circuit... Hope this makes sense....

Willcox

Rotonda

Suggest that you look at DocRebuild.com. He has 11x17 laminated color charts that have photos of each connector, their placement, what (and where) they connect to, and the color and gauge of each wire. They make life MUCH easier! I also have an early 77 and the dash harness part# is 8977101 and the ignition/balance of car is 8977103.

FYI, there is nothing behind the fuse box except a hole in the firewall leading to the bundle-of-snakes wiring coming out into the engine compartment.

Jim__H

Thanks Rotonda, I did see your reference to that in another thread. I might buy a set if I get in trouble again. BTW, you and I have talked before about your writeup on installing a Vintage Air unit in your '77. I refer to it often although I am going with the "stock" VA parts and installation. I am going to try to fab a center vent transition piece out of PVC or ABS tubing and sheet rather than make a mold and glassing it as you did. I'll let you all know how that goes.

So all the connections are on the back of the fuse box? Ok, that helps tracing since now I don't think I need to find some hidden terminal bus.

One new question for you all, does anyone know what the resistance of the rear defroster grid should be? When I throw the defroster switch the 20A Accessory fuse immediately blows. Measuring the resistance of the overall circuit I get less than 1 ohm, like ~ 0.3ohm which if accurate would certainly too much current for a 20 amp fuse. With the soldered connections at the window I am not sure what can be done, but I am wondering where a short might be and if I can find it maybe I can get it to work.

SwampeastMike

While those "all-in-one" wiring diagrams are certainly useful I find the individual circuit schematics (and descriptions of operation) from the shop manual invaluable when tracking down electrical gremlins.

Rotonda

1) My reference states that the grid resistance should be 5 ohms
2) it is possible to repair the soldered connections where the wires join the grid. I don't recall where I got the necessary materials & instructions, but I will try to find the source.
3) The wires are attached to the grid at either side are 2 to 3 feet long and terminate above/behind the rear fenders, under the carpet. The passenger's side is the ground and driver's side the power. Suggest that you disconnect the ground side, put in another fuse, and try turning it on. If the fuse blows, you have a problem at either the switch or the area where the wires are attached to the glass.

SUGGESTION:
The switch is a one year only part for the 77 and is pretty much irreplaceable. I didn't care for the amount of load it was carrying so I installed a relay in the cavity near the rear window. The relay is controlled by the original wire, and I installed a separate 12 gauge wire (with in-line 20 amp fuse) directly to the battery and terminated it with a Packard 56 terminal that plugs directly into the window power wire. It works fine and the strain on the switch internals is now MUCH lower.

Jim__H

I decided to punt on this one. Figuring that since I live in California, the car will be garaged all the time and I have interior RainX and plenty of small towels I can probably go without a rear window defroster. But that is some pretty impressive electrical re-engineering, Rotonda.