Electrical Issue No Power When Keyed On

[GaK10]

I have a 1986 K10 that has been sitting for a while. I didn’t have an issue with power when I parked it. Recently, I have been writing to fix it (nothing electrical was touched besides fuel tanks). I installed a good battery. The dome lights, the brake lights, the interior courtesy lights (floor lights), and the heads lights all work (didn’t try the turn signals). I have no power to anything else when keyed on.
I changed the ignition switch with no luck. Has anyone experienced this? Any idea what’s causing the issue? I’m not suited for electrical, an electrical mental block. Details and locations of hard to find components are appreciated.

 

[SirRobyn0]

Well. I'm good with electrical in person, but terrible where it comes to giving the specific locations you are asking about without standing there. Others on the forum tend to be better with knowing locations of things.

I think it would be good if you could give a list of things that don't work, otherwise we are left to guess what doesn't work and what wasn't tested.

But everything you listed that does work does NOT get power though the ignition switch, stuff like signals, radio, heater, do, so do those things all work or not work? Will the truck crank over? If so will it start and run? If not is there power the ignition + wire on the side of the distributor? Will the horn blow?

So more info needed there but almost sounds like ignition switch or a wire left off. I want to say fusible link, but I'd need to be standing there to confirm that.

Also this forum is big on introductions and pictures. Because this is your first post rather than an introduction it may turn some of the members off from answering.

If your not good at electrical, but are good at something else, I'd advise you to navigate over to that section and give your input on a few threads, investing in at least that much will tell us you are interested in giving as well as receiving.

Thanks and good luck with the electrical issue.

 

[GaK10]

I listed the things that work because nothing else does work. When I turn the key to any position, nothing comes on, no response at all from the dash, the radio, the ac fan, or anything else. Turn the key to start, nothing. No sounds, nothing it’s like it’s dead but with plenty of input power from the source.

I’ve replaced the ignition switch on the column and all is hooked up there. I’ve even checked the old switch with a meter and it’s good. I have also visually inspected the engine compartment and driver side under dash with no findings of anything disconnected.

I was saying not electrical by nature, I’m mechanically inclined. I am capable of figuring things out though. I’m not the best at diagnosing electrical systems. Seemed like everyone was on here to help everyone out, which I thought would be a good place to ask to see if someone had experience a like issue. It also appeared to be a form that I wanted to be apart of because we all share the same interests, GM square bodies. There’s vast knowledge on here. Are we supposed to give an introduction first? I overlooked that if members are.

The locations of things like fusible links is where I’m lost.

I have also been searching on here for like posts and haven’t came across one like this issue.

 

[SirRobyn0]

I listed the things that work because nothing else does work. When I turn the key to any position, nothing comes on, no response at all from the dash, the radio, the ac fan, or anything else. Turn the key to start, nothing. No sounds, nothing it’s like it’s dead but with plenty of input power from the source.

I’ve replaced the ignition switch on the column and all is hooked up there. I’ve even checked the old switch with a meter and it’s good. I have also visually inspected the engine compartment and driver side under dash with no findings of anything disconnected.

I was saying not electrical by nature, I’m mechanically inclined. I am capable of figuring things out though. I’m not the best at diagnosing electrical systems. Seemed like everyone was on here to help everyone out, which I thought would be a good place to ask to see if someone had experience a like issue. It also appeared to be a form that I wanted to be apart of because we all share the same interests, GM square bodies. There’s vast knowledge on here. Are we supposed to give an introduction first? I overlooked that if members are.

The locations of things like fusible links is where I’m lost.

I have also been searching on here for like posts and haven’t came across one like this issue.

I didn't mean to come off harsh and if I did I apologize for that. Of course an introduction is not a requirement nor is helping others, I just meant to say, I've see complicated problems from new members with no posts in threads other than their own thread sit. And I was merely making a suggestion that might get others to take a look. You could do an introduction post (there is a section in the forums just for that) and post a few pics of your truck and a link to this thread. I'm just saying it might help, not trying to give you a hard time.

 

[Itali83]

Clean the positive contact on the starter. Power comes from the battery to the starter then to the cab. Had a very similar situation with my 87 and ended up being a little corrosion there. Cleaned it and worked perfectly.

Ben

 

[GaK10]

Thank you Ben. I have seen some corrosion but haven’t checked any major points, including the starter and alternator. I give them a quick cleaning.

Out of curiosity, do you know where the fusible links are located?

 

[Itali83]

There’s one down by the starter. There’s two (on my 87 anyway) just above the rear of the left valve cover. On their way to the junction block on the firewall. Then there’s one off the alternator power wire that goes to the junction block. It’s by the front/mid right side valve cover where the harness lays by the intake manifold bolts.

Ben

 

[GaK10]

Is this a fusible link?

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[WP29P4A]

They don't put fusible links in wiring loom to keep them from melting other wires. The junction block on the firewall should have at least one fusible like attached to it.

Do you have a test light to test with?

 

[GaK10]

I have a meter. I may have put that in wire loom years ago to “enhance looks.” I believe that was the only wire in the loom. Is that typically what they look like?

 

[WP29P4A]

If you are talking about the vertical, thicker black wire in the center of the picture, with the dirty connector, with the bare wire sticking out of the top of the connector, no, from what I can see in the picture, that is not a fusible link. The red wire in the upper left corner of the picture looks like it could be one of the fusible links. Fusible links will be labeled in some way, either with the value printed on the wire or with some kind of "flag" that designates the value of the fuse. See examples below.

If you are talking about the terminal on the firewall with the red wire going into the split loom, you are in the right area. Do you know how to follow the voltage with your meter from the battery, to the starter, then to the junction on the firewall, then into the fuse panel inside the truck? Do you have the correct wiring diagram to follow.

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[GaK10]

Yeah sorry about that, this is my first encounter with fusible links. I’ve been researching them and a lot of other posts on this forum. Not sure what that disconnected wire with that “fancy” connector is but I’ll figure it out. Thank you for the pictures and the information.

I found the ’86 GM writing book online and have needed studying that to see where/how the power is distributed to the fuse block and the ignition switch. I started writing backwards, mainly from curiosity, due to power to the dome lights and lack of power, 1/2VDC, to the hot wires on the ignition switch. Afterwards, I ran out of time when I was searching for the links. Tomorrow (hopefully) I will be able to meter from the battery out and around the engine compartment. From what you said about the potential to destroy other wires if a link fails, I will confirm that there are no other wires with a link in a loom together.

I appreciate your help, thank you. I’ll update the thread when I find the culprit.

 

[75gmck25]

GM fusible links are usually one of two designs.

- Early trucks (like my ‘75) just have a piece of wiring in the loom that looks too fat and/or is a different color. If there are markings, they are usually very hard to see. I have this type of fusible link at my starter for the 10 gauge charge and power wires, and at the main junction for power to the fuse box. The fusible link section is 14 gauge in a 10 gauge wire, and it’s very easy to find GM fusible links to replace them.

- at some point GM started using links with a plastic barrel connector on them near one end. They might be a Metric fusible link, and the barrel or wire is usually marked with a number like .35, .5, 1.0. I’ve also seen some that are just marked with wire gauge on the plastic barrel.
I used two of them for my alternator charge wire (upgraded alternator) and to power my headlight relays. I got them off a GMT400 truck at the pick and pull. The larger one (blue) is the charge wire to the alternator and the smaller (red) one goes to my headlight relays.

 

[GaK10]

This is what I found. I checked all voltage from the starter, the alternator, the terminal block, and double checked the hot terminals on the ignition switch. I have voltage to all but the ignition switch. I rang out the wire from the terminal block to the ignition switch (the burnt one that I posted a picture of previously). The wire rang out.

It appears this has happened in the past and the previous owner spliced into the fusible link. However the link wire melted, not leaving much to work with. Does anyone know the size of the fusible link in this location? This wire comes off the junction block and splices into the 3 RED 2 wires that go to the ignition switch. The wiring diagram says M5/#10, but idk what that is relating too.

 

[GaK10]

I found some fusible link wire at LS wiring. I couldn’t confirm before ordering so I got 10-18 gauge wiring. The wire I posted (earlier in the thread) was the culprit and is a 16 gauge fusible link. Its fixed and all power has been restored to the dash, tank selector switch, ignition switch, etc. Thank you all for helping me.