New Harness & Wiring Questions

[greenacres]

I am installing a new wiring harness in my 79 K10. I’m not replacing an existing wiring harness. There are only bits and pieces of the original wiring harness left. I have a wiring schematic and I’m pretty good at reading wiring schematics. My problem is there are some connectors on the new wiring harness under the dash that I can’t figure out what they are for or what they plug into.

Attached are some photos of the wires I can’t figure out. I think one of those connectors goes to a seat belt buzzer, but I’m not sure which one. Any help would be greatly appreciated.

[bd]

Just glancing at the posted images, the connectors in images 1 & 2 plug up to the ignition switch.  Images 3 & 4 connect to the brake lamp switch (left & upper) and radio (right & lower), respectively.  Image 5 is a generic Series 56 connector used for various applications.  Without seeing the wire colors there is a certain amount of guesswork.

[greenacres]

Thanks bd. I'll see if that works.

[greenacres]

You are correct about the wires to the brake light switch.
I assume you are right about the wires to the radio, and I assume I can use those wires for my little stereo CD player.

I have already plugged one large connector into the ignition switch and it has all the correct wire colors. Therefore I don’t see how those other two connectors can go there.

The white connector has wire colors: yellow, brown, pink, light violet.

The black connector has wire colors: orange, pink, black with white stripe, brown with white stripe.

[bd]

The ignition switch uses two interlocking connectors, each connector pair is bi-colored (white/black, or less frequently, blue/black).  IIRC, the black connector must be plugged into the switch before its switchmate.  If you have only ONE connector already attached to the ignition switch, something is wrong.  Post a pic of the connector you currently have attached to the ignition switch.

[greenacres]

I am an idiot. I’m too embarrassed to say the mistake I made. You are correct. I have never done this before and it’s hard trying to figure out what’s what. Thank you, you have been a great help. I will probably have more questions later.

[greenacres]

Installing a new wiring harness in my 79 K10.
I have some more under dash wiring questions for you. I can't figure out where these things connect to.

Image 1 is a wire coming down out of the steering column. It has three very small gauge wires; black, blue, brown. I think that was for the factory cruise control?
I bought an aftermarket cruise control, and thought I would wait to install it after I know everything else is working okay.

Image 2 is a short blue wire coming out of the new wiring harness.

Image 3 is of three connectors at the top of the fuse panel.
A large black connector, a large semitransparent connector, and a small connector with a single beige colored wire.

Image 4 is a connector in the new wiring harness just left of the light switch.

Image 5 is a very very long black wire coming out of the wiring harness that connects to the dimmer switch.

Besides all of that: there is a white electrical connector down at the bottom of the steering column. I think that is what the wiring schematic calls “reverse light and neutral safety switch”. But I can’t find any connector on the wiring harness to plug into it.

[bd]

Installing a new wiring harness in my 79 K10.
I have some more under dash wiring questions for you. I can't figure out where these things connect to.

Image 1 is a wire coming down out of the steering column. It has three very small gauge wires; black, blue, brown. I think that was for the factory cruise control [switch]?
I bought an aftermarket cruise control, and thought I would wait to install it after I know everything else is working okay.

Image 2 is a short blue wire coming out of the new wiring harness.  ?? - From where does it exit the harness?

Image 3 is of three connectors at the top of the fuse panel.
A large black connector (probably horn relay, but it looks like the connector for the headlamp dimmer switch - possibly assembled incorrectly(?).  See if the relay fits the connector and locks into place.), a large semitransparent connector (seat belt warning buzzer), and a small connector with a single beige colored wire (maybe the park brake switch, but would require an extension - use a test light or ohmmeter to determine).

Image 4 is a connector in the new wiring harness just left of the light switch (w/w switch).

Image 5 is a very very long black wire coming out of the wiring harness that connects to the dimmer switch (seat belt switch).

Besides all of that: there is a white electrical connector down at the bottom of the steering column. I think that is what the wiring schematic calls “reverse light and neutral safety switch”. But I can’t find any connector on the wiring harness to plug into it.  (the neutral safety/reverse lamp switch uses two separate and distinct connectors - one square with purple & yellow wires, one flat with light green & dark blue wires, respectively)

All of the above responses are BEST GUESSES.

Didn't the harness arrive with a page of application notes?  Have you contacted the manufacturer for application notes or searched their website?  Don't be bashful.  The worst they can do is say, "No."

What is the color and gauge of the wire in the connector imaged below?

[greenacres]

Very little of this pickup is original. The cab came off of a different pickup and I think the cab is maybe from an earlier year.

I don’t know who made the wiring harness, it was purchased by a body shop that I won’t have anything to do with anymore. No instructions came with it, and there was no brand name on the package. There was a small label on the package that said this wiring harness is for a 1979 Chevy truck.

I called my local auto parts store and ordered a new horn relay to try in the large black connector at the top of the fuse panel. I already have a connector plugged into the dimmer switch and it is a perfect fit.

I already plugged a connector that is a perfect fit into the windshield wiper control. The colors of the wires are purple, yellow, green. The connector that you said goes to the windshield wiper control is the wrong size and shape to fit it. Maybe that connector is for a different year wiper control?

There are no connectors on the new wiring harness that will fit the reverse light or the neutral safety switch. I guess I would have to make my own wires for those two switches? I will do without those.

This photo is a close up of where the short blue wire comes out the wiring harness under the dash.

[bd]

That free hanging dark blue wire may be the power feed to the reverse light switch.  So, you might be half way there.

Don't bypass or eliminate the neutral safety switch or the vehicle will start in gear!  It's a foolhardy way to destroy property and injure or kill someone!  It is especially important if you have children around!  Although I've witnessed adults being pinned and hurt!

Purple, yellow, green are the wrong colors for the wiper switch.  On the other hand, pink, black, purple, gray and black w/blue stripe are the correct colors for the wiper switch.  You would be wise to take another look.  Post a pic of the wiper switch back and attaching connector.  The harness may be for a different year application.  But if the wire colors are correct and the connector isn't, a service connector might still be available with some legwork (GM superseded P/N-12117360 (ACDelco PT493), as derived from the factory wiring manual for a 1979 K10).

What color wire goes into the single wire connector that I asked about earlier?

[greenacres]

That single wire connector you asked about is on the end of the very long black wire that you said goes to the seat belt switch. I cut that wire off because I usually don’t wear a seatbelt and I hate listening to the seatbelt warning.

I took off the wiper switch and took a good look at the connectors I had on it; and I found the missing connectors for the back up light switch and the neutral safety switch. I figured out that dark blue wire hanging off the wiring harness had fallen out of the connector for the backup light, and I put it back in. Looking in a parts catalog, I found a picture of the wiper switch I have and it is for 75 to 77 trucks, and those two connectors plugged into it just fine. I will purchase the wiper switch they have for 78 to 83 trucks and I think it will probably work with the connector on the new wiring harness.
                           
You have been a tremendous help, and I doubt if I would have ever figured out those things on my own. Thank you.

There are a couple more things I can’t figure out.

Here is a photo of a small connector on the new wiring harness under the dash. The wire is brown.

There is a piece of the old wiring harness under the dash coming from the firewall. The wire colors are blue, green, brown, brown with white stripe, dark pink with black stripe. The dark pink wire does not go to the plug in the firewall like the rest of the wires; it is a long wire that exits the wiring harness under the dash, and whatever was on the end of that wire was cut off. Here is a photo of the plug on the end of the wires. And a photo what’s on the other end: a plug on the firewall in the engine compartment.
Do you know what this is, and is it something important?

[bd]

The center and lower images pertain to the dual fuel tanks sender selector wiring for the fuel gauge and solenoid.  The pink w/black stripe wire plugs into a fuse box IGN tap cavity using a keyed, neutral-color connector and PakCon terminal.  An assortment of OEM keyed connectors with the appropriate terminals are available from American Autowire (P/N-500429).

The solitary brown wire terminated in a Packard Series 56 connector is likely an accessory power tap for an appliance that will become more apparent as time progresses.

[greenacres]

Because my truck only has one fuel tank, I assume I don’t need that piece of old wiring harness and can throw it away?

[bd]

That depends on how the fuel gauge wiring is configured.  I recommend waiting until everything is operating before removing it, just in case there's a hitch...  If the dash and bedsides are punched for a selector switch and two tank filler necks you might consider holding onto the switch harness, if not for yourself for a subsequent owner who might be interested.

[greenacres]

The dash does not have a cutout for a gas tank selector switch, but the original cab did have that switch on the dash. The bed is brand new and has only one filler neck.