Passenger Side Fuse Blowing E 350 2007

[patrick51]

DaveB Yes there is a power outlet, so will check that after the exterior light. I disconnected the wire and was able to reinsert the fuse without blowing, so know its in the wire or fixture now. 6 lights and believe the h2o pump separate as it works. Too dark now. will let you know my findings P.

[daveb]

Glad you're on the right path. You can use a meter to test for a short like Greg posted and eliminate until you isolated the culprit.

[patrick51]

Sunday AM still searching,

[arctictraveller]

Originally Posted by patrick51

I have the original 07 seperator and think its the problem,somehow letting high amps through the fuse block.

Just to clear this up a bit, Any wire will try to conduct as much current as the battery, converter, etc will supply, possibly hundreds of amps during a short circuit. Pretty much every wire in you van (except the starter) is protected by a fuse or circuit breaker that limits the amount of current that can be drawn to what ever the safe limit of the wire is. Each wire has a maximum allowable current it can supply before it starts getting too hot, and in the case of a short, could possibly melt and catch fire. So, the seperator will pass as much current as it's fuse or circuit breaker will allow, but it can't push excess current into a circuit, causing a fuse to blow. Fuses blow when the current draw exceeds the designed limit of the wire, such as when there is a short. Hope that helps a bit.

[Roccon99]

I am having the same issue as OP...

I went to switch on one of my lights the other day and nothing happened. I checked the house fuse block and found that the passenger side fuse (30A) had blown. I went to replace the fuse and got sparks/melted tangs. I haven't changed anything or added anything to the circuit - didn't notice a particular issue that may have caused it either.

I started by switching all of the devices off and removing lightbulbs. Tried the fuse again, still sparking. I then went and detached all of the devices and disconnected the incoming power, still sparking.

As far as I can tell, there are 6 devices: 1 reading lamp by passenger side door, 1 bar lamp over the double side doors, 1 outside light with interior switch, 1 12v outlet by side doors, 1 reading lamp in rear passenger side, 1 bar lamp over the two back doors.

I attached my multimeter to the house ground and checked the incoming power at all of the devices. I set it to the continuity setting (little diode symbol, unfortunately I don't get an audible tone since I only have junky harbor freight meter). Every time I touched any of the incoming power supplies on each device, the reading would jump to 300 or so and then come back down to 001 and sit there.

I'm learning this stuff as I go, but that seems to indicate that there is a short in the circuit which all 6 devices are on. The only way that can happen (that I can figure out) is if there is a short somewhere in the single wire coming out of the fuse block, or where it splices to send out the 6 individual wires.

So, am I way off track here? Am I testing these circuits the right way? Any other suggestions to try and isolate the issue? If the issue is somewhere in that single wire/splice, where in the world do you think SMB put the splice? I see the wire coming out of the fuse block in plastic tube and into the rear side panel. I'm guessing it goes straight up and then splits its 6 ways from there. I'm hoping that the splice (if that's where the issue is) is up top near the upholstered cover as opposed to behind the veneer wall, since I don't see how I could access that.

Any and all help is greatly appreciated. Thanks!

[arctictraveller]

Originally Posted by Roccon99

I then went and detached all of the devices and disconnected the incoming power, still sparking.!

What you are trying to determine is if the power wire (from the fuse to the devices) is touching the vans metal body somewhere. With all devices disconnected (does that mean you removed the wire from each device?) you should not get continuity between ground (the metal body) and the wire from the fuse box. With your meter set on ohms, watch what happens with the leads not touching anything and then again by touching the leads together. Touching them together is the same thing as a short. Now try it again with one lead firmly touching a good ground on the body and the other on the power wire. It should remain the same as when the leads were not touching anything. If the reading changes, there is continuity somewhere in the circuit.

https://www.greatautohelp.com/Electr...To-Ground.html

[patrick51]

Racoon.

I went to the same conclusions, we never found the hidden splice apparently behind a wall panel, so deducted that the simple way was to run new wire to each fixture. Able to fish up from the block behind panel near the side door then to the front pass. light. and another to the ext light and on back. we removed a panel beside the rear doors to bring all the wires into a common location then put in a house type metal junction box then tied all together
the toughest was to fish from near the side door rearward at the top of the side interior panel but its possible. A wire was necessary across the floor under the bed so we put it in wire loom and let it lay on the floor under the bed where it is never seen or in the way.
We never found the short but assumed it was in the wall and could not be found without removal including window trim.
good luck. Nowdays there are lithium powered stick on light for those locations. Oh yes we could not fish to the ceiling penthouse rear reading light so abandoned it and if used we use a portable light up there. 2007 E 350 RB50.

[Roccon99]

Thanks, arctictraveler and patrick51.

I removed the incoming power wire from each device so there should be zero current on the circuit. When I touch the two multimeter leads together (on ohm continuity setting), the meter jumps from 1 up to 300 and then back down to 001. When I touch the black wire to ground and the red to the incoming power on ANY device, I get the exact same result...meaning that there is definitely a short in the circuit. I was trying to identify if it was a specific run, or device, that was causing the short. The issue is that ALL devices are giving me that short reading, meaning it has to happen somewhere at or before the splice after the fuse box.

As patrick 51 said, I'm guessing this happens somewhere behind the wall, which could be very difficult to access. Luckily I don't need or use any of these fixtures, so I'm not even sure I care to rewire, it's just annoying that they won't work. I may try and remove the top upholstered cover and see if I can see a junction there. If there is nothing there I may just be SOL.

[Scalf77]

Typically SMB run the 12 awg up along the behind the wall to to roof transistion, they then tap off of that wire with these wire taps.

Unfortunately your short could be anywhere on the line, most likely has worn through some where and touching the frame.

-greg

[Roccon99]

Originally Posted by Scalf77

Typically SMB run the 12 awg up along the behind the wall to to roof transistion, they then tap off of that wire with these wire taps

Thanks, Scalf77 - that is super helpful. I'm going to remove that bulkhead cover tonight and see what I find. Will post an update once I take a look.