Interior accessory electrical problems

[Lustle]

Hey everybody,

I'll start by saying that I'm new to the forum. And new to GMC ownership. I've got myself a 1987 GMC R1500. Daily driver/project truck. I've got a few things on the way. Powder coat flat black 15x8 rally rims and new BF goodrich radial ta tires should be this week. Maybe some new 2" inch beauty rings in stainless.

As for now though. I have one problem I can't seem to figure out. In the interior. My dome light doesn't work. My horn doesn't work. And my aftermarket head unit resets every time I shut off the electrical, but still runs with the key turned. The cigarette lighter doesn't work. I've checked the bulb on the dome, its fine. Usually these things are on the same circuit aren't they? I've checked fuses. They are fine as well.

Any ideas? Anyone come across this before? Maybe just a ground that needs to be hooked up?

If this is somewhere else on the forum I apologize. I tried searching. I've seen people with the horn out. Or dome light out. But never all the accessories.

Thanks for any help.

[bilfman]

They are most probably unrelated. Dome light not working is often corroded door switches. Take them out, there is a wire on them so don't lose it. Clean it with some wd40 and a scotch pad, see how it works.

Cig lighter can be corrosion in the socket, check the wire in the back of the socket it is a hot +, see if there is power there.

Horn can be many things. First thing to check is run a jumper from the + side of the battery and hold it on the horn spade connector, if it goes, horn is ok. Start working back from there. You can also use a 12v tester and see if there is power to the connector on the horn.

There is a start for you.

[nheller76]

I've got the same prob with my CD player, hope somebody has got an answer. BTW welcome this is the best place to get advise, I've rebuilt my entire drive train and the guys hear helped me do it.
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[1981Stepside]

The head unit has two power supply wires - a switched power (red) and a constant power (yellow) The yellow wire keeps the radio presets and clock after the vehicle is turned off. It is more than likely disconnected, or not connected to a constant power source. The other alternative is that the head unit is faulty.

[Greenlee]

If you think it's a ground issue, all of the inside the cab ground wires attached to prongs directly behind the A/C vent on the far driver side. They are actually attached to the emergency brake assembly if I remember correctly.
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[motornut]

Originally Posted by 1981Stepside

The head unit has two power supply wires - a switched power (red) and a constant power (yellow) The yellow wire keeps the radio presets and clock after the vehicle is turned off. It is more than likely disconnected, or not connected to a constant power source. The other alternative is that the head unit is faulty.

may want to check how it's "wired" in your truck
yellow is switched,orange from the lighter for memory
I suggest to run your own ground

[1981Stepside]

Originally Posted by motornut

may want to check how it's "wired" in your truck
yellow is switched,orange from the lighter for memory
I suggest to run your own ground

Meh. Red, orange, yellow- either or. Lol. Once I wired the radio and it works I haven't looked at it since. Looks like the memory isn't as sharp as it used to be. That's what diagrams are for. Thanks motornut.
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