Such a poorly marked fuse panel

[Cubey]

When I got the RV, the ignition switched power source wire for the battery isolater solenoid was pulled out from the fuse panel (a blade connector) because there were no house batteries installed, so there was no need for it to activate. It connects the house battery bank to the starting batteries when the key is turned, so the alternator will charge the house batteries too.

The two larger connectors on the sides go to either battery (doesn't matter which) and the smaller one needs 12V positive to activate the solenoid, so it needs to be activated only with the key turned.

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After I got a house battery put in, I decided to reconnected the tap to a fuse. I picked the one labeled "Seat Belt" 7.5A. I have non electronic lap only belts bolted to the RV seats, so I figured it was a totally useless fuse.

Well then the solenoid didn't seem to be working from what I could tell, so I replaced it. I thought it was working, but then it wasn't despite seemingly having power. It didn't seem to make sense. I thought the circuit breaker between the battery and the solenoid was bad, and was planning to replace it next week. But then I double checked it and found that it wasn't the problem. It had voltage on both poles with the ignition turned off, so power was getting power all the way through it.

So then I decided to jumper the battery directly to the solenoid's activation terminal, with the wire going to the fuse panel still attached. And guess what? It was activating the glow plug controller!! Basically I was feeding 12V back to the fuse and activating the glow plug system, where the wire was tapped into the "seat belt" fuse. So I think it was only activating the solenoid when the glow plugs were on? Or... something like that? I'm not sure, quite honestly.

I moved the tap to the radio fuse, since I have a very low power radio (no CD player, radio/mp3 only) and the radio fuse is 7.5A, and that seems to have fixed the problem.

So the "seat belt" fuse is actually for the glow plugs! Wow Ford, you really did a horrible job marking the fuse panel.

Here is a side by side comparison of a 1986 E350 gasser's fuse panel diagram from the web VS my actual IDI fuse panel. Fuse #4 is clearly marked "SEAT BELT" on mine, while on gassers it's "Fuel Tank Solenoid". I wonder if that fuse is also for the fuel tank selector on the IDI?

On the gasser, seat belt is lumped in with the W/S WIPER circuit breaker, marked #5.

(Post continues below)

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Fuse #11 on the diagram and my panel are both labeled radio, which is where the red wire is tapped into now and it activates the battery solenoid when the key is turned to run. I can also turn the key backwards to the accessory position, which turns on the radio but not the glow plugs, and now the solenoid activates in that position.

Fuse #3 is also marked really poorly, "MODULE"? What the heck does that even mean?! It's labeled "Throttle Solenoid" for gassers. When I got the rig, it didn't even have a fuse in "module" and everything seemed to be working fine, so I have no clue what it's even for. The picture below from February shows the module fuse missing, and the solenoid connected to the "Seat belt" but actually glow plug system fuse.

The rest of the fuses are marked identically.

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[IDIBRONCO]

I can't answer about the "module" fuse, but I don't think that the glow plugs are supposed to be on a fuse. I think that they usually get their activation power right from the ignition switch. I don't believe that Ford had anything to do with this mislabeled fuse.

 

[Cubey]

I can't answer about the "module" fuse, but I don't think that the glow plugs are supposed to be on a fuse. I think that they usually get their activation power right from the ignition switch. I don't believe that Ford had anything to do with this mislabeled fuse.

You would think the glow plug relay/controller would be fused, not the glow plugs themselves of course. Forcing power to the fuse without the key turned made the controller and relay work. It was cycling normally on and off, not forcing them to stay on forever.

Trying to find an IDI van schematic is just about impossible.

 

[IDIBRONCO]

Trying to find an IDI van schematic is just about impossible.

Where's Wes? The relay is just that, a complicated relay power in turns "on" and then the high amp power goes through. The controller is a timed, temperature controlled switch (although timed may not be the correct word here). By back feeding the power to the cold controller, you activated it to power the relay, which lets the battery power go through to the glow plugs. I'd say that the glow plug controller is getting it's power from the wrong location. It could be that something else that is wired to the solenoid in your first post is also tied into the same circuit as the controller is too.

 

[IDIBRONCO]

Maybe it's just time for that push button so that you can eliminate the power from everywhere else.

 

[Cubey]

Where's Wes? The relay is just that, a complicated relay power in turns "on" and then the high amp power goes through. The controller is a timed, temperature controlled switch (although timed may not be the correct word here). By back feeding the power to the cold controller, you activated it to power the relay, which lets the battery power go through to the glow plugs. I'd say that the glow plug controller is getting it's power from the wrong location. It could be that something else that is wired to the solenoid in your first post is also tied into the same circuit as the controller is too.

Nope. There's only 3 wires going to the battery isolator solenoid ("BIS"):

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The wire going to the fuse panel can't be the problem, since moving it to the radio fuse makes the BIS activate when I turn the key backwards to the ACC position, but not the glow plugs. I can backfeed power through the wire to the radio fuse and the radio comes on, but not the glow plugs. So we can rule that out.

The two poles on the sides ALWAYS have positive from batteries going to them, one side from the house batteries and the other side from the starting batteries. If the glow plug system was somehow tapped into either the wires going to the house or starting batteries, then it would ALWAYS be turned on, and would cycle non stop, which it doesn't. The glow plugs require turning the key to run to activate them. So we can rule those out too.

So no, it's not related to the BIS system.

The glow plug system is simply tied into the "seat belt" fuse, for whatever reason.

The only time the glow plugs got tied in with the BIS was when I had the BIS "fuse panel" wire connected to "seat belt" fuse, and backfeeded 12V from the solenoid's "fuse panel" pole, back to the "seat belt" fuse, by just temporary jumpering the "house battery bank" pole to to the "fuse panel" pole as a means to test of testing the BIS itself and seeing if the 13.8V from the house battery bank was connecting to the starting battery bank like it should with the BIS activated.

 

[IDIBRONCO]

So no, it's not related to the BIS system.

I'll try this once more despite the spinning head from trying to understand my great nemesis (electrical). ARE YOU SURE OF THIS? Since the BIS wasn't hooked to the solenoid before, you don't know if there is something attached to this that is also somehow tied into the glow plugs. It may sound stupid, but you know better than us what was done by a previous owner. Did someone else want something like a light to work without the BIS operational and tie another wire into the fuse panel without disconnecting the hook up to the BIS system? The glow plugs still should not have ever been tied into the seat belt fuse. This fuse should have been for either a seat belt warning light, a buzzer, or probably both from the factory. Is there a place for a seat belt light in your dash, even if it's not working? Was there ever a seat belt buzzer? Are these the factory seats? Since it was sold as an incomplete vehicle, they could have been changed out by El Dorado. I'm no expert on van technology, but since you said that the seat belts just attached to the seats, I'm guessing that these aren't OEM Ford. I believe that Ford and the other auto makers were required to attach then to the floor. If these were installed after your chassis left Ford, then who knows what may have been done to the wiring by either El Dorado or a previous owner.

 

[Cubey]

Nope, not factory seats. It is likely that the chassis left Ford without seats, since RV companies seem to always put in custom seats, carpet, etc. I doubt RV companies want to pay for seats that they have to immediately remove and toss into a pile when they get the chassis in order to put in ones with custom matching upholstery used throughout the rest of the rig.

You lost me on what you're asking about electrically.

Yes, there is a seat belt light in the dash. Never seen it light up. The "sensor" wires were probably spliced together someplace to fool it into thinking the seat belt is latched.