Electrical Issue - No Power to Dash

[Jambi]

I did a bonehead thing that ended up melting the ground wires to my radio and the heater and now I have no power to the dash. I've been doing a lot of reading on the forums and I think my culprit might be the fusible link going from the starter solenoid. Based on how it's been described in the posts I've read, I'm unclear if what I'm looking at is the fusible link so I just wanted to find out for sure. Is this the fusible link?

 

[DirtDonk]

Yes, that should be your main fusible link.
Is that yellow wire molded into it as well? Is that for the voltage regulator, or the horn relay?
I assume the voltage regulator, but I’ve never seen a double molded one on a Bronco like that. Seen them on other vehicles, but I can’t remember ever seeing them on Broncos.

Got a picture of it from the other side? Doesn’t look puffy or melted from here, but they are often hard to tell.
What year is the Bronco?

To be certain here, do you have no power to anything including headlights, horn, and brake lights?

 

[Jambi]

My Bronco is a 69. Yes, the yellow wire is molded into it as well. The yellow wire went to the voltage regulator, which I don't have anymore because I upgraded to EFI and the 4g alternator several years ago. I've read that yellow wire is no longer needed with the EFI/4g, but because of how it's molded in with the black wire, I cut it, put a wire nut on the end and left it. Not sure if that was the right thing to do, but that's what I did. What I'm not understanding is when I take the wire nut off the yellow wire and test for continuity and voltage (not sure if I need to test for both, but I did) I get both. If the fusible link was in fact affected, wouldn't I get nothing for continuity and voltage?

To answer your last question: correct, I have no power to anything at the dash including headlights, brake lights, etc. Also, when probing the center threaded stud on the back of the ignition switch shouldn't I be getting continuity and 12v? I get nothing. I also removed the black wire that attaches to that stud (this is the same wire that goes to that fusible link, correct?) and I get no continuity or voltage

 

[Oldtimer]

The wire connected to stud on ignition switch is to accessories. Black yellow wire from alternator on STOCK Bronco harness feeds power to ignition switch via a splice buried on harness. I think power to ignition switch is on yellow wire after the splice.

 

[DirtDonk]

Yep, the black with green wire on the ignition switch will only have power when the switches turned to ACC or ON.

I’m not sure you should see power on the yellow wire because I have no idea how it’s connected to the fusible link. However, it’s a good bet that with no power there the fusible link is blown.
I don’t really know how to test them unless there is a voltage drop test you can perform.

Being a 69, you have the two rectangular firewall connectors. Disconnect them on the engine compartment side and measure continuity and voltage between the fusible link ring terminal, and the black wire in the connector. Should be easier to test over that shorter distance.
And you could also inspect the connectors and make sure nothing melted inside there.
Shouldn’t be a problem, because that’s what the fusible link is supposed to protect.

 

[DirtDonk]

But speaking of those firewall connectors, pulling them both and inspecting all the connections and wires is a good idea now and then.
Make sure they are clean and rust free. And no silvery white oxidation on the surface that would impede electron flow.
Probably install some proper grease/sealant. I still use dielectric grease, but there are those here that can better explain what the good bad and ugly is of using that particular product. Maybe there is something better for this application.

 

[Oldtimer]

This and attached PDF may help in tracing your circuits.
Not sure how 4G alternator is connected, and what it changes on these schematics.

 

[Jambi]

I got a new 16g fusible link wire, attached the ring terminal end to the battery side of the starter solenoid and used a butt connector to attach the fusible link wire to the black wire. As @DirtDonk recommended, I disconnected the rectangular connector at the firewall, engine compartment side and measured continuity and voltage between the fusible link ring terminal, and the black wire in the connector. I got 12v and continuity there. I reconnected the rectangular connector at the firewall and then checked the voltage and continuity at the bullet connector under the dash where the black wire connects with the black wire with the yellow stripe. I got 12V and continuity there. After plugging the black wire to black with yellow stripe wire bullet connector I was getting 12v at the fuse panel, which I wasn't getting before.

Success! I now have headlights, brake lights and my Dakota Digital speedometer lights up. Now an issue I'm trying to work out is my fuel pump isn't kicking on when turning the key to the "On" position. I have an in-tank fuel pump. I disconnected the pink fuel pump power wire (I have the Ron Francis EFI harness) to see if I'm getting 12v switched power to the wire and it doesn't appear that I am, so I need to figure out what's going on there.

 

[Oldtimer]

Does the EFI harness have a fuse or relay in the fuel pump circuit?

 

[serial car restorer]

The RFrancis panel has a dedicated fuse for the fuel pump (pink wire). Has you checked to see if it is blown?

 

[Jambi]

The RFrancis panel has a dedicated fuse for the fuel pump (pink wire). Has you checked to see if it is blown?

Yes, I checked the fuse, relay and inertia switch and all are good. I put my code reader on and I am getting a 95, which, according to the book I have is "Fuel pump secondary circuit fault". Not quite sure what that means, so need to do a little research on that one. Hopefully it's nothing too serious.

 

[EPB72]

Yes, I checked the fuse, relay and inertia switch and all are good.

so you have battery voltage at all those points the inetia switch is last in line to pump?,, battery voltage at pump side of inertia switch.... then use a rubber mallet and give bottom of fuel tank a little wack, {in tank pump?] or if you can get to wiring at top of tank confirm power and ground..

 

[Jambi]

While I checked switched voltage to the pink wire with my voltage meter and wasn't seeing a 12v reading with switch "on", I thought I'd check with my continuity test light and it lit up. Attached the pink wire back up to the fuel pump connector on my gas tank and the fuel pump is now kicking on. Everything seems to be working now. I should also mention I did get a new ignition switch, which I think helped with the issues I was seeing as well. With my old switch removed I did a couple continuity tests between terminals on it based on a couple videos I found online and I wasn't getting anything. So, I got the new ignition switch and everything is working. All in all, it seems the issues I was having was related to the both the fusible link and the ignition switch.