Smelling Lights

[RussW]

Good morning,

I just got my 98 Expedition running after a heater core replacement. Runs great until night time. At first there are no dash lights or lights on the door switches. Eventually the lights come on dim but after about 5 minutes there is a smell like wiring insulation getting hot.

I am going to change the headlight switch. Any other ideas or suggestions?

Thanks.

 

[ArtGamer60]

sounds like an electrical short , was it happening before the dash removal ?

 

[Jeff532003]

My guess is there's a pinched wire in there somewhere or a short to ground. If you have a volt meter you should be able to check restiance to confirm. Cross my fingers that you don't have to pull the dash again.

 

[RussW]

The only incident prior to the dash removal was 3 years ago in Florida in a rain storm. All of the dome lights and courtesy came on along with 4X4 indicator light. I unhooked the battery over night and it has been fine ever since. Three years later I remove the dash for the heater core and now have the smell issue.

There is no smell with the lights off. If I turn the lights on everything works normal except the dash illumination and the illumination for the buttons on the doors. I drove about three miles with the lights on before the dash started lighting up slowly. It was another 8 miles before I detected a slight aroma.

Today I tried several times to get it to repeat itself but the dash lights never came on.

In my simple mind I would think a positive wire going to ground would eventually blow a fuse and a weak or poor ground would cause the wire to over heat and produce the smell.

I have ruled out over voltage because the lights are either not on dim and gradually get a bit brighter. I have seen over voltage cook the insulation but I dont believe that is the case here.

The only place I could have possibly pinched a wire would be when I re-mounted the steering column. I may have pinched one but I cant see any obvious wires. I will drop the column to double check.

Thanks for the replies.

 

[stamp11127]

A short to ground on a power feed will blow fuses. What your describing is an overloaded circuit that is heating the wire insulation. Not good.

I'd pull the headlight switch and check the harness leading to it. Also as you stated, the steering column for pinched wires. If you disconnected any grounds, check those also.

 

[ArtGamer60]

It depends ? not in a loop ? the good ole smell of burning or melting pvc ...

 

[RussW]

So far no luck. Today I pulled the dash and look all around. Cleaned and reapplied the grounds, turned headlights on and wiggled wires, swore a few times, wiggled some more and still no dash or door switch lights. No pinched wires either and all fuses are good.

The headlights, tail lights and markers all work fine, just no interior dash or switch lights.

I pulled the headlight switch and have 12.8 V to the switch. When I turn the switch on I have power to all wires in the plugs except the black wire (assuming ground) and the yellow wire right beside it (assuming I dont know what it is)

I will have to find a wiring schematic and see what the yellow feller does.

 

[toms89]

A short to ground on a power feed will blow fuses. What your describing is an overloaded circuit that is heating the wire insulation. Not good.

I'd pull the headlight switch and check the harness leading to it. Also as you stated, the steering column for pinched wires. If you disconnected any grounds, check those also.

This is true but bad connection somewhere is more common. Broken wire can have the same symptoms. Bad connection = resistance = heat. Resistance = voltage drop and dimming lights.

Look for signs of corrosion or burning of connectors.

 

[toms89]

A "mild" short for lack of a better word could have similar symptoms if it is not a dead short. The short needs to have low enough resistance to draw enough current to "blow" or overload the fuse.

But I would put my money on bad connection or semi broken wire...

 

[toms89]

After reading the thread over and you mentioned you had similar incedent after big rain storm sounds a bit like water in the gem/fuse block may be causing your issues.

 

[RussW]

I really appreciate the replies. I have found no signs of anything that looks like it got hot or is corroded.

I will have my wife ship my manuals to me here in Maryland so I can start taking apart the harnesses and see what trouble I can get into.

 

[toms89]

I really appreciate the replies. I have found no signs of anything that looks like it got hot or is corroded.

I will have my wife ship my manuals to me here in Maryland so I can start taking apart the harnesses and see what trouble I can get into.

What part of MD??

 

[RussW]

My office is in Timonuium and I live in the Jacksonville/Monkton area