With 5 trailers all purchased from the same company, dont you have some kind of tech support help from the trailer manufacturer???Or how about warranty coverage? Assuming the trailers wiring is factory, not done by the FD, it sounds like a design flaw......Now if the wiring has been modified or altered by FD guys, maybe electrical wiring isnt there forte....If the mechanics couldnt find the ground short, how could they positively identify that was the problem, something just doesnt add up

 

Funny you mention the fuse...one of the five would blow a fuse every time the umbilical was connected. They found whatever was causing that and fixed it, but the drain persisted.

 

Out of warranty (of course). These were bought before I joined the program and before I took over as Operations Chief. Once I did I had them run in to the Corp Yard and told them don't send it back without a fix. A month they sat and fiddled with it...their final solution was a cutoff switch. Keep in mind the interior is finished with wiring up the walls between the outer shell and the interior sheeting...so to truly 'fix' it they'd have had to completely disassemble the interior sheeting to view the wiring (which of course they refused to do since wiring in a $6 switch "solved" the problem).

...no, we haven't added any warning lights to these rigs at all - the wiring is as stock as it was when delivered - all they did was add in the cutoff switches.

...ah, actually, it IS their forte. You don't buy utility trucks pre-wired and lighted, you get a pretty red blank truck and you add all your own wiring, light bars, MDFs, sirens and any other gizmos you want on it to meet your departments setup. These guys know their stuff inside and out. If they determine the cost/benefit of fixing it right isn't worth it, unfortunately I have to live with that since it's taxpayer money that pays their labor...but when they tell me it's problem X, then it's problem X.

 

That's the problem...the "time" part. These aren't "first in" apparatus like engines or trucks or ambulances...they are disaster response vehicles that (rightfully so) get put on the back burner. So long as they keep the tires/suspension/brakes working and the contents dry and lockable, they consider it serviceable.

...such is the cost of a volunteer section of a government entity.

 

Assuming the company is still in business, you should be able to get a wiring diagram from the company, warranty period or not.........At one time your dept spent a LOT of money with this company, correct?
assuming the lights are individually fused at the circuit level, i.e interior lights and exterior floods, you should be able to pull fuses or open breakers, then with the cutoff switch in the "on" position, determine which circuit is at fault be removing and replacing the battery ground, you shouldnt see any spark at all.
Again assuming you can figure it on one trailer, you then could logically assume its a common flaw, and make the decision on whether or not a true fix would be cost effective.
These trailers may also have discussion forums, brand related........Every other thing we drive or tow has enthusiast forums, have you looked into this?

 

There lies the issue, they are NOT individually fused, there is one fuse in the battery box and that's it.

 

So you have a single power lead running into the fuse, and either a single wire running downstream into the walls of the trailer, with a connector/junction block that separates the 12V power into leads for each light fixture, OR, you have individual leads coming directly out of the fuse or fuse block heading downstream into each individual light circuit? As i asked before, do these trailers have an enthusiasts online forum? If so, and all 5 trailers have the same issue, that suggests a design flaw, and you guys CANT be the only ones that are having a problem?