Radio Wire and/or Connector

[vespaholic]

My newly acquired 1979 C20 is missing its factory radio.
Fortunately, the PO did not cut the dash.
Unfortunately, I can not find any of the original wires at all.
Nothing is cut and hanging down; nothing.
No speaker wires either.

The truck came from the factory with an AM ONLY Radio.

I pulled up the carpet and found these (PICTURE #1)

The one on the right I believe is for the seatbelt buzzer.
So, I will not reconnect that.

The connector in the second and third pictures is the wire in question.
It was tucked behind the wiring harness as if to get it out of the way.

PINK with BLACK STRIPE = Power with ignition switch on. No power with ignition switch off.

ORANGE = Nothing Under any condition I can think of.
Ignition or or off, nothing
Lights on or off nothing.
Accessory position, nothing.

Is this the radio connector/wire for an AM radio?

If not, what is it?

Anyone have a pic of where the radio would connect to the harness?

Thanks!!!

[Desert_Eagle02]

What year is your truck? Last summer I replaced my factory AM only radio in my 78 with a Retro Sound unit.

Here is a pic of the back of the original AM radio.
On the right side is where the connector goes. It has the following wires
Ignition Switch
Wire to light switch (light in the radio that comes on with dash lights)
Ground
And then speaker wires.

The circular connector on the bottom left is for the antenna.

I do not have a pick of the wire connectors themselves, just the back of the radio.

[vespaholic]

The truck is a 1979. (I fixed the original post)

Thanks for the pic.

OK, I'm guessing the wire I'm questioning is not for the radio.
What is it for then?

Weird that there are no visible remnants of the original radio wires or connectors.
They either hid them well or cut them within the harness somewhere.
I'm at a loss!

[ray_mcavoy]

The 1978 & newer GM radios (like the one in Desert_Eagle02's photo) used connectors like the ones shown in the attached pic.

The blue plug (if used) is for the rear speakers. It's part of the rear speaker harness and will only be present in trucks that had rear speakers.

The white plug is for the front speakers. It's part of the front speaker harness. And for the mono radios with the center dash speaker, the front speaker harness was simply a short section of wiring that ran directly from the white plug (at the radio) to a plug into the speaker.

The black plug is for the power, ground, and dial light. This plug and it's associated wiring is part of the truck's cab / dash harness and should still be present unless someone has cut it off. The wire colors are yellow for switched power, black for ground, and grey for the dial light.

Finally, my pic also shows the black 2-wire connector (with brown & orange wires) that was only used in trucks with the optional digitally tuned radios.


EDIT, I believe the 2-wire plug with the pink/black & orange wires shown in your 1st post is for a TH400 kickdown switch that would be mounted to the bracket directly above the throttle pedal. The round plug with the black & white wires looks a bit like the ones used in 4x4 trucks for the 4 wheel drive indicator light (but seeing as your truck is a C20 it might be for some other purpose).

[vespaholic]

@ray_mcavoy: Thanks for the detailed pic and description.
Based on this my truck would not have the blue connector.
I have not seen the white nor the black connectors anywhere under the dash or through the radio hole.
I guess I'll have to start pulling the dash apart and see if someone hid them or cut them.
If they cut them they sure did a good job of covering their tracks.
Thanks

[ray_mcavoy]

You're welcome!

The yellow, grey, and black wires (for the black connector) should be branching out of the cab / dash harness somewhere fairly close (like 10" or so) from the radio location.

If your truck still has the original front speaker(s) in the dash, you should be able to follow the wires back from them to find the white plug. But if the original front speaker(s) are gone, their wires (along with that white plug) were probably taken out too.

I believe the OE style 78+ GM radio connectors can be purchased as pigtail assemblies (plugs with a few inches of wire attached) from many auto parts stores & online vendors. So if yours are missing (and you can at least locate the cut wires in the harness) you can splice in some new ones.

[vespaholic]

I pulled the dash top off to see if the factory speaker was still there (it is not) and to look for the original radio wires.
I found them, picture #1.
So installation of the radio I just ordered should go smoothly as it comes with factory pigtails.

I also found the connector next to the steering column. Picture #2.
I this where the connector (pictured earlier) with the pink/black & orange wires should be connected?
Can anyone think of a reason why that would have been disconnected by the PO?
If not for the found connector, what is this for?

Thanks!

[vespaholic]

OK, my bad.
Clearly the connector (pictured earlier) with the pink/black & orange wires is not for the connector on the steering column.

But I still need to know what the connector on the steering column is for.
Can anyone help.
Thanks

[TKCR]

You really need to get a wiring diagram. That would be so much more helpful. I believe a member on here, hatzie, has downloadable diagrams.

[Dead Parrot]

Does/did your truck have factory cruise? The black thing just above the blue tag in pic 2 post #7 looks like a cruise vacuum disconnect. Thinking the connector might be cruise related. Especially if there is a push button on the back.

[vespaholic]

@Dead Parrot:
It did have cruise control.
That makes sense.
Thanks

[BHTH]

Right you are.

http://67-72chevytrucks.com/vboard/s...d.php?t=545416[

QUOTE=TKCR;8180805]You really need to get a wiring diagram. That would be so much more helpful. I believe a member on here, hatzie, has downloadable diagrams.[/QUOTE]

[vespaholic]

@BHTH That's a great resource.
Thanks!