1979 Chevy Radio wires

[Iamsoocluess]

The cigarette lighter wire would be your constant hot.
Most old vehicles didn't come with a radio that needed a constant for memory.

Do you know why my cigarette wire isn’t working?

 

[CalSgt]

Do you know why my cigarette wire isn’t working?

Are you testing it with a test light? or does the lighter just not work?

First thing is make sure you have a good ground for your test light (well, actual first thing is to disclose if there are any other electrical things that don't work before you start)

Next check the fuse (mine shares a fuse with the horn), you can also check continuity from the lighter wire to the fuse box to see which circuit its on. You may get continuity on several circuits, pull all of those fuses and check both connections of each fuse slot to narrow it down. If you don't get continuity on any circuit the wire may be cut or disconnected somewhere.

All my pictures are from a 1980 so your stuff could be arranged slightly different

You must be registered for see images attach

If the fuse has power on both sides work towards the ashtray from there to see if it's been cut or disconnected somewhere.

If the fuse has power on one side, replace it. If it holds you should get power to the lighter wire. If it blows you have a short in one of the orange wires inside the cab.

The stuff below would also knock out some other electrical circuits... so if the cigarette lighter wire is the only issue you shouldn't need to go this far.

If it has no power on either side, try again with the key in the run position if still no power on either side check on the engine side the firewall at the wiring bulkhead. Check to see if theres power at the two heavy red wires on the big plug by probing them at the bulkhead. One of them comes from the alternator and Y's at the positive bus bar to the left of the brake booster on the firewall, the other comes off of the positive lug of the starter. IIRC the lead coming from the starter is the one that feeds the light and horn circuits the other feeds the ignition circuit. if you don't have power at one of these check the fusible links theres one at the starter and two at the bus bar IIRC.

You must be registered for see images attach

If you do have power at both heavy red wires disconnect the bulkhead connector and inspect the pins and receptacles to see if one of them is blown/burnt out. You're primarily just looking at the pins that go to the heavy red wires. Getting the bulkhead harness apart is a PIA, it's practically glued together with black goo. My pins have been removed and cleaned so don't expect them to look like this.

You must be registered for see images attach

If it got hot enough to burn out one of the receptacles the plastic around it will probably be partially melted or burnt. You cant judge them on the look of the plug itself because the black goo prevents good visual inspection. Again, you would mainly be looking at the two that correspond to the heavy red wires. In this picture I think it is the one on the top right that goes to the starter positive and one row down second from the left that comes from the alternator.

You must be registered for see images attach

 

[Iamsoocluess]

Are you testing it with a test light? or does the lighter just not work?

First thing is make sure you have a good ground for your test light (well, actual first thing is to disclose if there are any other electrical things that don't work before you start)

Next check the fuse (mine shares a fuse with the horn), you can also check continuity from the lighter wire to the fuse box to see which circuit its on. You may get continuity on several circuits, pull all of those fuses and check both connections of each fuse slot to narrow it down. If you don't get continuity on any circuit the wire may be cut or disconnected somewhere.

All my pictures are from a 1980 so your stuff could be arranged slightly different

You must be registered for see images attach

If the fuse has power on both sides work towards the ashtray from there to see if it's been cut or disconnected somewhere.

If the fuse has power on one side, replace it. If it holds you should get power to the lighter wire. If it blows you have a short in one of the orange wires inside the cab.

The stuff below would also knock out some other electrical circuits... so if the cigarette lighter wire is the only issue you shouldn't need to go this far.

If it has no power on either side, try again with the key in the run position if still no power on either side check on the engine side the firewall at the wiring bulkhead. Check to see if theres power at the two heavy red wires on the big plug by probing them at the bulkhead. One of them comes from the alternator and Y's at the positive bus bar to the left of the brake booster on the firewall, the other comes off of the positive lug of the starter. IIRC the lead coming from the starter is the one that feeds the light and horn circuits the other feeds the ignition circuit. if you don't have power at one of these check the fusible links theres one at the starter and two at the bus bar IIRC.

You must be registered for see images attach

If you do have power at both heavy red wires disconnect the bulkhead connector and inspect the pins and receptacles to see if one of them is blown/burnt out. You're primarily just looking at the pins that go to the heavy red wires. Getting the bulkhead harness apart is a PIA, it's practically glued together with black goo. My pins have been removed and cleaned so don't expect them to look like this.

You must be registered for see images attach

If it got hot enough to burn out one of the receptacles the plastic around it will probably be partially melted or burnt. You cant judge them on the look of the plug itself because the black goo prevents good visual inspection. Again, you would mainly be looking at the two that correspond to the heavy red wires. In this picture I think it is the one on the top right that goes to the starter positive and one row down second from the left that comes from the alternator.

You must be registered for see images attach

 

[Iamsoocluess]

Mine looks a little different

 

[Randy and Easton]

@CalSgt great reply! Spot on…

@Iamsoocluess , different fuse block but same principle. You have old glass fuses like we do but finding what is powered or not is the same. Start as Calsgt said and you will eventually figure where you are losing power.

We always started at the end of the run like the cigarette lighter and worked backwards. What we found , thanks to the guys here is that most of the time it’s one ground wire that is pinched or a power line that is broken especially with blown fuses. Take your time and as you work these issues the understanding follows and it all starts to make sense

Randy and Easton

 

[Long Rider]

I have installed several Retro Sound radios in my old cars and in 2 square bodyC10s. In the photo if you look at the flasher in the upper left-hand corner, right below it you will see two places, either one of which will work for your switched power, just put a spade (male) end on the wire your running to your red wire on the Radio and connect them. You can run your constant hot to the wire that feeds the cigar lighter as WFO already suggested or you can run it to the fuse block. There are two constant hot that accept the spade connector just to the left of the flasher that is at the bottom right of the photo. If you run into problems you can also call Retro Sound in Las Vegas and a technician will be happy to help you too.