I was half way up my 1.5 mile driveway today when my 2003 F250 truck shutdown. No lights & no dash lights. The battery tested fine. I checked all the fuses under the steering wheel. All good. Is there another 'main' fuse somewhere that could have gone? Any other ideas or tips on how to troubleshoot this issue? Thanks. Richard.

 

Look at the drivers inner fender in front of the master cylinder. There is a black terminal block with one stud on it. The wire likes to rot off there. Just splice the 2 together.

 

Also check the battery (and alternater) csbles - make sure they're in good condition and have tight/clean connections

 

there is NO master main fuse...

only bad batteries.. bad cables.. bad connections.. bad grounds.

 

There are 2 #12 gauge fusible links wired in parallel between the battery and the left fender. These supply a power to most of the 5-20 amp fuses.

 

I should have mentioned initially that my F250 is a 5.4l gas model. The battery is on the passenger side (I think diesels are opposite).

So yesterday, after posting but before any replies, I decided to go back to the truck and try to locate an engine compartment fuse box. That process involved moving a lot of wires out of the way (I have a plow and it has a ton of wires). I didn't find a fuse box. This morning when I (and a neighbor) went back up to check for bad grounds, he wanted me to turn the key on for some reason (forget what) and the dashlights came on. Apparently, all that moving of wires had corrected the issue (well not corrected, there's still an issue somewhere).

I did confirm that there's a good ground going to the frame (near the starter). There's also a bare braided ground wire that connects to the firewall (high on the passenger side). It runs down behind the engine somewhere. I pulled on it and it seems quite strong.

To alloro's point, I just watched this video ( ) on replacing fusible links. I wouldn't have known what a fusible link wire looked like before watching the video. It seems like a good candidate. Now I just need to locate them, wiggle them, and see if things act up.

I had posted back in Feb about how my dashlights had started to flash a pattern during a warm spell, but it went away when things got cold again. The group had suggested a bad ground which I planned to investigate when the weather got warmer (and the dash flash started again). It hasn't yet, but could all be part and parcel to whatever happened when the electrical died last Sat.

Thanks for all the replies. :-)

I'll let you know what I find. Any other suggestions also welcome.

 

Why do fusible link wires even exist? It seems to make things much harder to troubleshoot and repair versus a regular fuse.

I haven't had an opportunity to check my fusible links yet.

 

They are more durable than fuses and don't burn as fast as a fuse would blow. This allows for temporary high loads that a fuse wouldn't be able to handle.

 

Ah. Thanks. Good to know.

 

i wont go into all the details, but check the wire bundle that comes out of the fire wall to the fuse box and then down the frame underneath the truck, they will be covered in an aluminium colored heat shielded wrap. What you may find is if you get on your back and move the bundles, you might find chaffing that exposes the wires inside the bundle. You wont notice on the top side, only with a flashlight underneath checking where the wrap touches the frame. then wrap the bundle, and zip tie it away from the contact points of the frame. let us know if you see that and take some pics if you do.

 

163junk was right on the money. I reproduced the problem by starting the truck and then moving wires under the hood. Was expecting it to be a fusible link. As I moved the wires near the firewall access hole the truck turned off. Took a while to find the problem but eventually spotted a wire that wasn't connected to anything. As per 163junk "Look at the drivers inner fender in front of the master cylinder. There is a black terminal block with one stud on it. The wire likes to rot off there. Just splice the 2 together.". I was expecting to see an exposed stud, but it's covered with a cap. When I removed the cap the stud was quite corroded. Touching the broken wire to the stud caused the electronics to power up. Just need to figure the right way to do the repair. Here are some pics for reference. Thanks to everyone for the advice (and 163junk in particular).

 

Thanks for taking time and responding with pics. Most often people just get on the forum to get thier problem diagnosed then they fix it and we don't know the outcome. In your pic it looks like the burnt out wire on the right side of that cap probably attached to that stud. Might spend some time and figure out what it goes to in a wire diagram and then see if its something you need powered up. that cap has two indents on either side making me think that was designed for two wires to be attached to the terminal. Maybe not but curious anyway.

 

Replace the terminal and splice some new wire, with a new ring.
The other wire is corrode, too.
Get rid of that rusted mess.

 

A butt splice kit would work good in this situation.
https://www.lowes.com/pd/Morris-Prod...ectors/4618522

 

The wire(s) on the right go back into the fuse box. Same thing happened on my 03' with the 5.4. I doubt you'll get that terminal box to work again, cut the ring connectors on both sides and install new ring connectors. Get a bolt with 2 lock washers and a nut, bolt them through nice and tight, wrap with electricians rubber tape, nice and heavy and you're good to go.