Half of fuse box not working!

Make sure you check that AM1 fuse on the working side of that fuse box before you do anything else..

 

I would check for 12V on both sides of the AM1 fuse first. Then I would set my meter to continuity setting and check for continuity between the AM1 fuse leg and the white AM1 wire on Pin#4 going into the ignition switch. If you don't get a beep, the wire is broken and not continuous.

You certainly could temporally provide 12V into the Ignition switch on the white wire for testing. I would be careful here and make sure you are on the correct wire. Don't want to make the problem worse.

I would assume doing this temp fix will make everything function like normal. Then all you have to do is find the break in the white wire between the fuse box and the ignition switch. Pull the plastic around the steering column off and start looking.

 

Yea its kind of an interesting design. This setup means that one fuse AM1 can take down power to like half the truck. If it goes out you never pass any interior fuse box power through the ignition switch as the key comes on.

 

Just saw your question about the alternator. Its not working because the 7.5A LH-IG fuse is not getting power inside the interior fuse box. Fix the problem with the fuse box and the alternator should start working again.

The 7.5A LH-IG controls an ignition on signal to the alternator. This enables it to start charging based on ignition input.

 

So I have gotten the fuse box to this point to try to check continuity in that white power wire. This is the DD connector in the back of the fuse box. Does anyone know if this DD connector can unplug? Because I cannot even begin to try to probe with all the wires that close together unless I get the connector out

 

Unclip the black plastic latch and the arm should open up. It will pop right out

 

So I do have continuity between the white wire at the ignition and at the DD pin. I also have continuity between the am1 fuse and the pin on the back of the fuse box.
So one weird thing is in my photo with the pins, the am1 fuse pins out to the bottom left pin which i believe is pin 60
The white wire going to the ignition pins out to the second green pin illustrated in my photo which i believe is pin 47. This makes me think that they dont actually connect at all, unless this happens internally somewhere, but i dont see that in the wiring diagram
I am also getting no continuity from ignition white wire to the 7.5 am1 fuse when this dd connector is connected to the box

 

I am also getting no continuity from ignition white wire to the 7.5 am1 fuse when this dd connector is connected to the box.... This is where I could focus.

You should get constant power through the AM1 fuse, out Pin 47 of DD and into the ignition switch.

The 7.5 AM1 fuse goes directly out of the fuse box to the white wire on Pin#47.
Pin #60 is the ground leg to close all the relays.

I would study the Pinout connector diagram to make sure Pin# and Wire colors match with what they should be.

I would be double checking for continuity from Pin 47 at DD into the back of the ignition switch. White wire.

If it is making a good connection and the fuse is good you should have 12V at the ign switch but you dont.

 

That is very odd that the am1 is toning out to pin 60 on the back of the fuse box. The white wire is on Pin 47 and is 100% getting continuity all the way to the ignition switch. Very odd, I called a mechanic friend and said the last option is a bad fuse box. I just don't see how that would have gone haywire

 

But your not getting 12v on the white wire at the ignition switch right?

Did you test it with a jumper to see if applying 12v to that wire fixes everything

 

Well if anyone wants an update and for others in the future that have this problem, I bought a used fuse box off ebay and replaced my current one and voila everything works. Not sure how the fuse box went bad but something wasn't right, it was the last line of failure that I could diagnose and sure enough that fixed it. Who would thought

 

Wow, glad you fixed it.
Were there any signs of water or rodent chewing damage on the old one?

 

No not at all. It must have been something internal inside like a loose solder connection, I'm going to take the old one apart and see what it looks like in the next couple days

 

Of the 20-30 similar issues like this I have seen here, this is the first where an entire ECU failed.

I would be interested to see inside of it as well.