f/w junction block to fuse block

[mjck5]

I'm trying to clean up my wiring harness on my 86 k5 that was butchered by previous owners, i think I've got it pretty much all back together except for one wire, its a 10awg wire coming off of the firewall junction block (10awg wire has a inline fuse spliced into it at junction block) and running into the cab and is spliced into an orange (looks like 18awg) wire that looks to be power for a clock, when i unhook them my horn doesn't work and the cab lights get all funky (stay on with door shut turn off when door open) so I'm pretty sure I've figured out this part of the fuse block is supposed to get power from the junction block but id like to know where exactly the power wire from the junction block is supposed to tie into the fuse block, if anyone has any info or pics that would be great

 

[CalSgt]

I wonder if your bulkhead connection is burned up…

If I read your post correctly someone bypassed the bulkhead and ran an orange wire into the cab instead of through the fuse block?

There should be two 10 ga wires routed from the junction on the firewall to the bulkhead connector, each should have a fusible link. This is their position on the bulkhead on my 1980…

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if overloaded the brass connectors burn up and melt the plastic around the connector. I don’t have an example of a burned up bulkhead but here is what a healthy one looks like. There’s different ways of repairing a burnt out connection, on way people do it is to cut out the connectors, splice the power supply wire, pass it through the bulkhead and splice it behind the fuse block.

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[mjck5]

is this pic from the engine side or the cab side?
heres what mine look like in the engine compartment at the fire wall

 

[Jgonick]

Attached is power coming into fuse box- It tells were it is coming from. Dark grey in the fuse box is the power going to fuses.

Here is a link to wiring diagrams- download and look at 86- shows how the wiring runs. I would suggest quickly reading the first few pages also-very useful info to know. I wonder if a previous owner spliced in a fuse instead of replacing a fusible link. (If so, I would replace it with a fusible link.-)
LINK-to wiring diagrams

 

[Jgonick]

See attachments. Shows how the wires originally were. First number is size of wire (metric) Then color of wire, then circuit number.

 

[CalSgt]

is this pic from the engine side or the cab side?
heres what mine look like in the engine compartment at the fire wall

My first picture is the same as yours just out of the truck and cleaned up. That big section of wires is actually 3 separate connectors that snap together before you bolt the plug into the bulkhead.

The 2 red 10 ga wires in your picture are the ones that supply the fuse box with power.

My second picture is what it looks like when you unbolt the connector and wiggle them loose.

Let’s see a picture of your orange wire with the fuse…

 

[mjck5]

the fused on is coming off the firewall junction block, under the dash they have it tied into the orange wire which is plugged into the top left spot on the fuse block, according to wiring diagram that is to feed power to a clock which my k5 doesn't have, also looks like all the fusible links have been removed from the other wires on the junction block, it looks like all the original wires are there feeding threw the bulkhead connector

 

[Jgonick]

Previous owner screwed up your wiring. It appears they are back feeding that portion of your fuse box by that red (fused) orange wire. Not good really.

What happens to your tail lights when you unplug the wire (with parking lights on)?
Also is your horn/dm fuse good?

I'm not quite sure why your cab lights are working at all when the red/orange wire is unplugged

In attachment-you can see it is supposed to be fed by red-2 (bottom left) That is the same red wire I labeled on your bulkhead in previous post #5

I'm betting they ran one red wire from starter to junction block. Then two red wires from junction block to the bulkhead. The red fused wire-I know. Where does the other red wire on the junction block go? Alternator?

 

[mjck5]

Yeah it’s been a adventure fixing all this, when I started the running lights would be on any time the key was on, if I turned on the running lights at the switch I could turn on the heater a/c fan whether the key was on or not, I put in a new headlight switch and found where they had the blower power and running lights power tied together and separated that so now that part pretty much works except now there is nothing connected to the brown wire off the headlight switch which I understood was power for the running/tail lights, but they work like they should, when I unplug the wire from the fuse block the horn doesn’t work, the dome light comes on about half bright but only the dome light comes on not the one under the dash, and if I hit the horn the dome light goes to full brightness, and if I open the door which should turn on the dome light it turns it off, when I plug it back in everything seems to work as it should

 

[mjck5]

Also checked all fuses and they are all good, havent traced all the wires off of the junction block have just been focusing on the one with fuse, so far it seems the rest of the wires in engine compartment havent been hacked up, i know one goes to the relay on the blower motor im assuming one is going to alternator

 

[Jgonick]

Too complicated for me to figure it out over a forum. My suggestion is to download 86 wiring diagram LINK and go over it a circuit at a time. Or invest (if you have the money) in something like a Painless Wiring Harness and rewire everything. LINK- Painless Harness

 

[mjck5]

Yeah it’s a mess that’s why I’m taking it one wire at a time, I’m probably going to have to pull the bulk head plug off and see if there’s anything going on in between the connector and fuse block, right now just want to figure out how to get rid of the wire back feeding the fuse block