Another wiring post
Thread Starter
Pro
Joined: Oct 2011
Posts: 554
Likes: 82
From: San Jose CA
Another wiring post
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
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
Last edited by Jim__H; Jul 13, 2018 at 03:21 PM.
Safety Car
Joined: Oct 2007
Posts: 4,380
Likes: 1,746
From: Seattle Area Washington
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/
http://repairs.willcoxcorvette.com/1...cer-schematic/
Last edited by bmotojoe; Jul 13, 2018 at 05:06 PM.
Thread Starter
Pro
Joined: Oct 2011
Posts: 554
Likes: 82
From: San Jose CA
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/
http://repairs.willcoxcorvette.com/1...cer-schematic/
I just fixed the parking light/turn signal problem and a couple of other loose ends so for now I'm good...
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
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...
I just fixed the parking light/turn signal problem and a couple of other loose ends so for now I'm good...
Willcox
Burning Brakes
Joined: Sep 2006
Posts: 1,071
Likes: 86
From: Rotonda FL
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
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
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.
Thread Starter
Pro
Joined: Oct 2011
Posts: 554
Likes: 82
From: San Jose CA
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.
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.
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.
Melting Slicks
Joined: May 2015
Posts: 2,365
Likes: 428
From: Cape Girardeau Missouri
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.
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Burning Brakes
Joined: Sep 2006
Posts: 1,071
Likes: 86
From: Rotonda FL
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.
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.
Last edited by Rotonda; Jul 15, 2018 at 08:18 AM.
Thread Starter
Pro
Joined: Oct 2011
Posts: 554
Likes: 82
From: San Jose CA
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.
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.
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.