Wire harness meltdown

[Phil's X]

I'll spare you the puzzle and go straight to my tentative analysis:

The "static suppressor", "noise inhibitor", or whatever you call it, [part # f6af-18801-aa] is intended to quiet the 12 volt line that feeds the spark generator. I assume it's just a capacitor; but it could be more. It is bolted to the top, front, right corner of the spark coil with a single wire from the wire harness plugged into it.

I suspect the failure began with a short to ground in the suppressor.

Not enough of a short to blow a fuse...

Every fuse slot that I know of has the right amperage,

and none appear to be blown.)​

... but enough to melt the insulation on the wire and then thru the plastic tube ...
... and thru the jacket on the green wire in the next plastic tube

leading to the temperature sensor on top of the thermostat housing.​

Despite the heavy current, the hot wire was still hot electrically,
so it applied +12 v to the temperature sensor wire.

I don't know what that would do to the temperature sensor.​

Engine runs fine sans suppressor, for now,

CD player sounds good.

Don't listen to radio,

out in the boonies;
​

"Service Engine Soon!!!"

Any wire in the harness

could be shorted to +12...​

One turns off O/D.

one fires the ejection seat;

please not that one!​

Start shopping junk yards;

Can't afford new wire harness;

nearest is 10 miles.​

No extra driving;

no cellphone to call for tow;

shine up that thumb.​

 

[Phil's X]

Advice to eXplorer owners:

Install an inline fuse where the +12 connects to the suppressor. I'm guessing 1 amp would be sufficient. If the inline fuse blows, you'll hear "zzzzzzzzzzzzz" on the radio; no affect on the engine.

The other fuse on that circuit kills the ignition after the wire harness melts down, maybe.

I wonder how many makes and models have this looming problem.