Blown Ignition Fuse Every time it Rains Heavy

[jseen]

Vehicle: 2007 Ford Explorer Sport Trac 4.6L 2WD

When it rains heavy, and I try to start my truck it blows a fuse.

From some googling, it appear there is a short, likely from exposed wires. Is there a way to "quickly" identify where the short is coming from the ignition or just follow wires till I find a nakey-boy?
Also, there there any wiring diagrams available online? I can't seem to find any that are still available.

 

[Bazz270]

Post your burnt fuse number and ill try to take a photo from a factory diagram

 

[jseen]

Post your burnt fuse number and ill try to take a photo from a factory diagram

I'm not 100% sure what you mean by fuse number but here is a picture of the fuse info. It's fuse number 8 (Ignition switch power)

 

[Bazz270]

Please:

And here is the "U" power distribution:

Check your windshield drain channels.look for SJB soaked with rain water

 

[jseen]

Please:
View attachment 433089

Thank you very much. I'll report back after I swear at the truck for several hours and likely brake something.

 

[Explorer75]

I would check the starter ground or the starter load. With heavy rain I would guess the bottom of the engine bay and the parts near the grille would get wet.

 

[jseen]

Check your windshield drain channels

Checked. They are clear. And SJB didn't seem to have any water in it.

I would check the starter ground

Looking under the truck, I noticed there is a red wire that goes from the fuse box to the starter. Next to it, a white wire with a green strip is not connected. I'm wondering if this was a problem for the previous owner and they did this as a fix (not sure though).
@Bazz270 do you know what the white wire with a green strip going to the starter is?

Also, I noticed the rubber grommet for the main wiring harness was slightly raised on one side as if it wasn't seated in 100%. I'm wondering if a trickle of water is getting in, and running down the wires to the SJB. Thinking of trying some duct tape to see if this is the source of the issue.

 

[Explorer75]

Checked. They are clear. And SJB didn't seem to have any water in it.


Looking under the truck, I noticed there is a red wire that goes from the fuse box to the starter. Next to it, a white wire with a green strip is not connected. I'm wondering if this was a problem for the previous owner and they did this as a fix (not sure though).
@Bazz270 do you know what the white wire with a green strip going to the starter is?

Also, I noticed the rubber grommet for the main wiring harness was slightly raised on one side as if it wasn't seated in 100%. I'm wondering if a trickle of water is getting in, and running down the wires to the SJB. Thinking of trying some duct tape to see if this is the source of the issue.

I´m not an expert but my best guess is:
red wire that goes from the fuse box to the starter (+)
white wire with a green strip is not connected (- or ground) you need to check the schematics to re-connect it. My guess is that the starter is getting the ground (very bad ground source) from the metal body touching whatever it is touching. When you have lots of water you lose the little ground you had and the amps jump through the roof and the fuse is blown.
Re-connect the white and green wire to its location and I believe your problem will be solved.

 

[bdmaash]

the battery grounds to motor and chassis
this is where the starter gets it's ground
check and clean ground and power terminals on both sides (engine and battery)
If you have a bad ground fuses do not blow : there isn't a path from power to ground to blow the fuse.

Fuse is blowing because there's extra current draw on the circuit

 

[jseen]

the battery grounds to motor and chassis
this is where the starter gets it's ground
check and clean ground and power terminals on both sides (engine and battery)
If you have a bad ground fuses do not blow : there isn't a path from power to ground to blow the fuse.

Fuse is blowing because there's extra current draw on the circuit

@Bazz270 @Explorer75
Update. After finding the "loose" wire. I isolated it and wrapped it in electrical tape.
It has since rained (a few times very heavy) and the fuse hasn't blown. My working hypothesis is the white and green wire is the original load. For some reason they ran a new one (red wire). The old wire (white and green) might still have current and when it rained, allowed it to jump to the starter and overload it. (My complete guess. Will probably blow now that I'm typing this).

 

[bdmaash]

@Bazz270 @Explorer75
Update. After finding the "loose" wire. I isolated it and wrapped it in electrical tape.
It has since rained (a few times very heavy) and the fuse hasn't blown. My working hypothesis is the white and green wire is the original load. For some reason they ran a new one (red wire). The old wire (white and green) might still have current and when it rained, allowed it to jump to the starter and overload it. (My complete guess. Will probably blow now that I'm typing this).

very good hypothesis, personally I would just snip that white/green wire as far back as possible to the harness, and seal the harness - then nothing comes loose and shorts out again (if it's hanging loose)

 

[jseen]

very good hypothesis, personally I would just snip that white/green wire as far back as possible to the harness, and seal the harness - then nothing comes loose and shorts out again (if it's hanging loose)

My only reserve with doing that, is if I need the wire later (perhaps a bad install). If I clip it and stich it, I'd have to solder a new connection if I need it again.

I'll roll with this for a while. If no issues, I'll do what you suggested