1978 radio wiring

[howlinghuskoe]

Can anyone show me what the radio wiring will look like on my 78 gmc Sierra? I bought it with no radio in it and no antenna which I'm thinking is supposed to be on the side of the passenger fender I will post a pic of the wire I think it is when I can. I know at one point the truck had a radio cause its cut out for it on the bezel and the paint is scratched from the nuts

 

[350runner]

Welcome from Texas!

Sent from the dust in front of you!

 

[howlinghuskoe]

I think I figured it out I think someone had an aftermarket radio in it at one point its got a single white plug with a metal box before it and the wires were just twisted together and wrapped in tape I will post a picture when I get home it won't let me from my phone

 

[chengny]

In addition to the speaker wires, there should be three other wires coming from the trucks harness and tied into the aftermarket adapter wiring.

A yellow - switched power supply. Only powers up the radio when the ignition switch is in the RUN or ACC positions. The radios supplied with these trucks did not use a constant battery feed like today's head units.

A gray - power for the display backlighting. This is part the dash board lighting circuit and varies according to the dimmer rheostat.

A black - the ground connection.


As far as speaker wiring - you are on your own. I would use the factory speaker leads if they still exist (and the truck was equipped with the 5 speaker option).

 

[howlinghuskoe]

I believe there is and there's also a red wire which was added in and I believe it came from the factory with just the two dash speakers but someone added two but there just set on the floor behind the seat they were probably added when the radio was put in

 

[howlinghuskoe]

I also think the aftermarket wiring might be the same color as the standard wire colors

 

[bucket]

In addition to the speaker wires, there should be three other wires coming from the trucks harness and tied into the aftermarket adapter wiring.

A yellow - switched power supply. Only powers up the radio when the ignition switch is in the RUN or ACC positions. The radios supplied with these trucks did not use a constant battery feed like today's head units.

A gray - power for the display backlighting. This is part the dash board lighting circuit and varies according to the dimmer rheostat.

A black - the ground connection.


As far as speaker wiring - you are on your own. I would use the factory speaker leads if they still exist (and the truck was equipped with the 5 speaker option).

My old '79 K5 had a stock radio that had power at all times. I believe it came from the factory that way, the truck was a completely original base model. My others have all had switched power, but they have not been base models either.

 

[howlinghuskoe]

There's also a orange wire with a black stripe is that a radio wire?

 

[howlinghuskoe]

I think I figured it out but would like someone to confirm what I'm thinking will a truck with radio delete say that on the options list in the glove box and will a truck with radio delete have the dash cut out? The wiring I found is cobbed together and none of it goes into the truck harness it has no speakers in the dash

 

[bucket]

I think I figured it out but would like someone to confirm what I'm thinking will a truck with radio delete say that on the options list in the glove box and will a truck with radio delete have the dash cut out? The wiring I found is cobbed together and none of it goes into the truck harness it has no speakers in the dash

The radio was an option, so no "delete" option. The hole was cut in the dash and bezel, it would just have a blank plastic cover on the opening.

Does your windshield have the antenna in it? It would be a pair of really thin stripes in the center of the window, with a black button connector at the bottom.

 

[howlinghuskoe]

No antenna in the windshield there's a whole in the passenger fender on the side for an antenna