I’m getting ready to reinstall all of the wiring harnesses into my 69 and am working to educate myself on how to wring everything out on the bench so when it is in the car, I’m fully prepared to quickly troubleshoot issues. While I do all of my own work, volts, ohms and amps have never been my strong point so I am taking the time now to fully understand how the whole system is designed to work. I know the basics but am pretty much over the top OCD and need to dive into the rabbit holes to understand the why and how.

I’ve collected a lot of resource material on electrical systems and just finished assembling a very large wiring diagram member @robertea recently posted. One of the first steps I am trying to take is identifying which wires are energized when the battery cable is hooked up, then identifying which are energized when the key is turned to each of the positions.

In studying the diagrams, my curiosity was piqued when I noticed that the 12R wire off the starter solenoid is connected to 14BRN, which is then connected to 10R (all in series) before terminating at the horn relay. I’m sure there is a solid reason for this but at first glance it doesn’t make sense to me. It is these kind of questions that I’d like to know if there is a good resource available to refer to.

I have found some posts by @Richard454 and @Peterbuilt that have been helpful on electrical issues but I don’t want to be spending countless hours searching if someone can identify a good, comprehensive resource.

 

Following.
are you installing a new wiring harness? If so, from where?
I have my harnesses to install next on my list and they are fr9m Lectric limited

 

At this point, I have not made the decision to replace any of them. Once I have my game plan for checking them out, I will do a thorough physical assessment of their condition.

If I were to replace them, I’d likely get from Lectric Limited tho as I have bought from them before.

 

The factory didn't publish a electrical trouble shooting manual for the 69 model year. However most of it is the same for a early 77 model. They did change the main power hookup from the horn relay to a bus connection block. And a few other minor differences. None the less.
the factory Electrical Trouble Shooting Manual for a 77 is like a wiring a Corvette for Dummy's book. Every circuit is explained as to how it's supposed to work. And all the schematics are broken down to the individual ciruits.
You might want to find one.

 

The LEFT side of the fuse box gets power when the battery is hooked up.
The RIGHT side gets power with the key ON.

 

Thanks @4-vettes and @Peterbuilt !

 

Kevin, As you go through your wiring harness issues if you find any errors in my wiring diagram let me know what they are and I will correct them.
It is a continuous "work in progress". I have found a number of errors in the GM Wiring diagram, but I am fairly sure that there others that I have not found.
Working with others on the Forum I updated the file in December with a missing wire in the ignition switch connector.
Bob

 

The laminates are Dr. Rebuild’s OSoEZe’s
Will do Bob. Can’t thank you enough for what you’ve done to digitize it. 53” x 17”!

 

There are a couple fusible links in the harness which essentially is a smaller gauge wire in series with a large gauge wire as the small will melt first. Rewired my 69 and all went well as it will for you. I made some changes as recommended by Mark Hamilton at mad electrical. Check out his website and the "New System". It is what I used under the hood to accommodate headlight relays and electric fans. Read the whole site as there is a lot of great information there.

Read this:

http://madelectrical.com/electricalt...evymain1.shtml

 

Thanks!

 

One of the interesting characteristics of the wiring on a 69 is what current actually goes through the ammeter. That current is not the full current of the charging system, but a shunt (i.e. a parallel path) of smaller gauge wires which carry a fraction of the current that goes through the larger gauge wires that actually power the big stuff. That way you don't blow out the delicate mechanism in the gauge.

You can puzzle it out from the factory wiring schematic and it may be worthwhile to study your alternative schematics to see if they've captured that factory design decision. And as well, any new harnesses.

Whe you add large draw electrical accessories, failure to provide that shunt path trips up what the ammeter should be showing. Myself, I switched the ammeter to a voltmeter when I put in my electric fans, but both mechanizations have their own value.

And I've found the Doc Rebuild colorful graphics to be worth their money. I have them taped to the inside of my parts cabinet doors.

 

Thanks @ignatz !

 

I have updated the 1969 Wiring Diagram again. No major changes, but some Forum questions about Wipers got me looking at GM's drawing and I found a couple of errors.
Also put files out on Wiper Vacuum and Wiring Diagrams to try and make working on that system a little easier.

 

Thanks to @robertea I am making good progress on figuring out how this system works. Can someone identify and explain the purpose of this “device” that the two connectors as shown plug into? It is attached, I believe, to the steering column. This is the original harness on my December 1969 production car.

 

That is your ignition switch, turning the KEY switch moves a rod to energize different systems in the car.

 

It is the ignition switch that mounts down on the steering column where it is difficult to reach on purpose. In my photo the switch is kind of shown in the orange circle and the rod that goes to the key mechanism is in the green circle.
If it has been removed from the column as it appears yours has then it has to be realigned before you install the column.
A new switch comes with a small plastic pin that locks the switch so that you can align it with the key mechanism so that when you turn the key the rod moves to the correct location, otherwise nothing works correctly.
It is fairly east to do and you could probably fit something into the hole to align it. I can probably look tomorrow to see if I still have the alignment procedure. Note: Fixed columns and tilt columns take different switches.
They are kind of opposite of each other, don't know why. The green piece is the plastic pin.

 

Thanks @robertea and @Peterbuilt . This car has been disassembled for 35+ years so am slowly working my way through boxes and reacquainting myself with all the parts! I have a tilt/tele that I acquired many years ago but since I need to shorten the column for my Borgeson, I think I’ll just stay with the original column.