1995 E350 Blowing Fusible Link, Vehicle Loses All Power

[gtbensley]

I will get it in the shop tonight and start fixing stuff and isolating that circuit.

On a different note the gentleman who sold me the van just texted me with the information that this has happened to him while using the inverter, but at a low idle. He never had to replace a fusable link though, only reset the breakers that are mounted on the drivers seat and or unplug the inverter. Probably a similar issue but doesn't seem the same as I had the inverter off this last time it went.

 

[gtbensley]

Previously I could run ALL my lights without an issue. Outside floods and all to light up the whole vehicle. Never noticed a problem with the lights themselves although I have noticed that when I use my blinkers they no longer indicate on the cluster when they are used....but they work fine.

I honestly cant remember if I had the lights on the first time it went. I had my high idle and turned on the microwave (yup, that draws a lot). The second time I had the high idle and the parking lights on. Pulled the switch for the driving lights and it shut off.

 

[gtbensley]

I found this

And this


But this is the one I replaced with a 14g


That also indicates without ambulance package while mine states it has it right on the door.

 

[Bikersmurf]

For comparison sake, mine has a 4 Guage(ish) wire from the alternator to the battery isolator. It's around 1/4-3/8" of stranded copper wire... From what I've read, that's on the smallish side.

 

[gtbensley]

Yeah I have a feed similar to that as well. This fusible link in the diagram above I would think it was a 12 gauge? For the life of me I cant tell where it goes or what it does. It cant carry much of a load.

 

[Mwilliamshs]

I found this ...also indicates without ambulance package while mine states it has it right on the door.

It actually indicates both WITH and WITHOUT. It's basically two diagrams in one. You can just look at the ambo stuff and ignore the rest. Strangely enough, your van apparently says Ambo package in the door but it has fusible links where the diagram shows ambulances as having a fuse (300 amp) instead. Think about that. Even with two big alternators (say 130 amp 3Gs) that fuse is way bigger (40 amps) than would be needed except that it needs to be sufficiently larger to prevent melting. A 100 amp fuse will blow with an instaneous surge of 100 amps but will melt through from a sustained say, 80 amps. Ford uses a 150 amp fuse to protect their 130 amp alternators, which tracks pretty well with the 130 amp 3Gs I mentioned and the 300 amp fuse on the diagram. Fuses aren't bad, but they require compromising via oversizing to compensate for their poor heat resistance and heat is inherent with fuses, fusible links, etc because it's their impedance that makes them work.

Reviewing the diagrams (especially the second of three pics, the second diagram, lower right side) I only see a couple dark green (14 GA- DK GRN) fusible links there but they're not the main alternator feeds. I see one for the PCM which would kill the engine, its sensors, etc but shouldn't kill lights, etc but it also feeds the engine compartment fuse panel (IDM relay, PCM relay, etc) and I think that's the bingo moment you're looking for. Battery to fuse panel to fuse box to load...it's a chain and you have a broken link.

 

[gtbensley]

Well apparently I am an idiot.....the links not blowing. It's removing the two positive battery cables and re installing them that's doing something.
The van has sat for a few days, was running when I parked it. I just went to get it going and bring it into the shop and it had no power. I checked the link, battery in place and it seemed fine. I pulled the battery positive battery cables as it has three positive ones and imidietly re installed them and had power. I wiggle tested the harnesses......they are fine, no change at all. It's like any decent current draw is popping one massive relay. And pulling the positive cables reset it. Makes no sense right? Yet I just spent twenty minutes with it running and can't seem to get it to over load again and go. I haven't tried the inverter but I can run ALL my lights, fans, radio and nothing is blowing.

Who wants to buy this haha? I'm getting fed up.

And I just found this drawing, for my van from the up fitter. Can't understand it though

 

[Mwilliamshs]

Glad you're making progress. I'm at work (snowed here today = OMG everyone come to the hospital STAT) so I couldn't follow up on your PM. Sorry. Arkansas SUCKS at handling wintry precipitation and I get called in for every little thing.

I would pull batteries and have them tested.

 

[Bikersmurf]

I feel your pain... There is a light at the end of the tunnel... Just can't tell you how long it is. Mine wouldn't crank till I thumped the dash (randomly of course). I eventually 'fixed' it... And by that I mean, It has stopped doing it...


I'm real curious what the M-714 does.

Some of what I read, is that you've got a 4 guage wire going from the Alterantor to a 200 amp shunt (fuse I believe) and then to the center terminal of a diode type alternator which isolates the two batteries from each other.

M-714 looks like it monitors the two battery voltages and likely connects them together... when the engine is running? Or ______?

Ambulances often use breakers that can be reset... But it almost sounds like a circuit breaker that's staying tripped till power is removed?

I'd be checking all your grounds, cleaning them till they shine, and reinstalling with never seeze or other grease of choice. Worst case, you can rule out grounds.

 

[Bikersmurf]

You could even have an 'Anti-Theft' circuit which allows the truck to run and charge after the key is removed from the ignition... Till you release the parking brake or touch the brake.

 

[Mwilliamshs]

...you've got a 4 guage wire going from the Alterantor to a 200 amp shunt (fuse I believe)...

Shunts are low-resistance conductors of known impedance used to create alternate current paths. They are most often seen with ammeter gauges where the ammeter reads the current in the shunt (which is proportionally lower than the current in the main circuit) so a smaller ammeter can be used. Without a shunt a vehicle with an ammeter and a 130 amp alternator would need an ammeter capable of constantly flowing 130 amps, minimum. Instead a 5 amp ammeter can be used thanks to a shunt, and have far less risk in doing so thanks to fewer high-amp connections, etc. Shunts are kinda like mechanical oil pressure gauges where the guage reads the pressure in a small tube running between the gauge and the block instead of the whole gauge being threaded into the oil pump.

EDIT: the pen and ink drawing posted above shows the 200 amp shunt near the image center and has two leads running through 20 amp circuit breakers labeled as "TO AMMETER" where a greater current on the positive lead coming from the shunt (alternator side) will show a charge on the gauge but a greater current on the negative side (starter and main power side) will show a discharge.

 

[Mwilliamshs]

...I'm real curious what the M-714 does...M-714 looks like it monitors the two battery voltages and likely connects them together... when the engine is running? Or ______?...

http://www.amazon.com/Ancor-714-140A-DVSR-Battery-Selector-Switch/dp/B00BO89OOK

DVSR: dual voltage sensing relay.

Basically anytime the batteries are being charged (engine running, plugged in to 110v, solar, etc) the DVSR will connect them so leisure and start batteries stay charged up. They're typically set so the start batteries get charge to a certain point (sensed voltage) before the charge gets shared amongst all the batteries. The difference in a DVSR and a VSR is the dual voltage senses both leisure and start batteries so they can be connected to share a charge coming from either side, engine (alternator) or auxillary systems (solar, shore power, etc). The one I linked too also has a manual switch for isolating or connecting the batteries regardless of charge state, like for jump starting the engine with the leisure battery, etc.
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The OP rig doesn't have the DVSR I'm guessing but instead the old, inefficient diode isolator with a big aluminum heatsink. Nothing wrong with it per se, but there are better, more efficient ways to do the job nowadays. The M-714 switch is layed out on the right side of the pen and ink, shunt output goes to isolator center terminal than to M-714 to be connected to either bat 1, bat 2, or both and based on the M-714 top center connection being to Ign. Circuit Breaker #4, I'm guessing the batteries are connected anytime the key is on.
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Back to the shunt, its input comes from the alternator via a 4 awg red wire. This wire is probably where the fusible link blew, more accurately the fusible links were likely at the alternator's connection to the starter solenoid which is probably where the alternator and this 4 awg cable meet since those get used as junction blocks a lot of times. Lack of power here causes lack of power to isolator and to the M-714 which causes loss of power to whole rig unless m-714 is manually switched to pair battery banks.
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Like a car with keyless entry remotes, when the remote battery dies you have to unlock the doors manually or in this case, when the fused link blows, you have to switch the battery banks manually but you'd still not have alternator power for recharging so you'd not be driving far.

 

[Bikersmurf]

Makes a lot of sense about how the shunt works in the system, I'd not want to have 215 amps running to my dash guage... Logically I knew that must be the case, the meter is simply not big enough to handle that kind of juice.

 

[gtbensley]

You some smart guys. Thank you!

I will trace my wiring some more and see if I can find any of these items you speak of. I am not sure where my 20 amp circuit breaker would even be. And of course last night I couldn't get the system to over load and cause the problem again. Had every light and fan on and she was running great, charging great, and seeming to have no problem.

The fusible link I thought was an issue clearly is not. When I disconnected it I still had power to the whole rig. It would crank but no start so my guess is that feeds into some injection control module. Give it power and it would start right up.

The problem really just seems to be a massive disconnected or breaker somewhere in the system.

 

[gtbensley]

Last night I cleaned all the battery connections and replaced clamps. I did find a very bad one on the side post battery that powers up the cab. Looked fine until I removed it and found lots of corrosion and a poor connection.

I replaced that and the terminal on the battery. Fingers crossed but that just might have been it.