Sparking in all the wrong places...heater fan & horn

[Hey_jude]

So I'm on a date with my wife on Friday and we're sitting eating some ice cream.  The car is running cause my key ignition switch is starting to fail.  As I sit there we notice a funny smell then I see some smoke coming from what looks like the steering column.  So I shut off the car, pull the batt cable and tow the car home on a roll back.

Saturday I get a moment to open up the dash.  I pull the Steering wheel, the dash cluster, the ash tray and ignition switch to "look" and see if there is any obvious charring.  There is none.  I hook the batt up and wait to see if I can see anything, and there's nothing.  I run the car looking intently for smoke but don't see anything.  then out of the corner of my eye is see arcing.  The heater/defroster controls are loose and the fan is in the on position.  And it is arcing from the control panel to the metal dash, turn the fan control off and it stops.  It's only a few millimeters away but still its clear as day.  Then today I install a new ignition switch and put it in place.  Again I start the car and check the controls and same result.  Arcing when the fan is in the on position. 

Then just for grins I hit the horn and it shoots sparks out of the ring in the wheel that makes contact with the horn.  Tried it again with the same results. 

I can't imagine this is normal or right.  What on earth is going on? I'd love some help if anyone has run into anything like this before or has any thoughts...Thanks.

Jude

[shelbydoug]

The insulation on wires has definite life expectancy.

It sounds like there is wire to wire contact somewhere in the harness itself.

The 68 Mustang column wiring harness coming from the directional switch is one place where the wires are compressed in order to fit into the column. It's one of the places that I would look since so much of the wiring of the controls is routed through it.

Other then that, talk to Coralsnake. He's done a lot of work in recreating wiring harnesses for the '68s and may be able to pin point the spots in the harness to look at.

My car has documentation of wire harness issues new, under warranty, and it stemmed from this issue of the insulation on the wires themselves being bent too much in assembly of the car or even in the construction of the harness. So far, the repairs done 50 years ago are still good but finding the problem in a wiring harness hidden in the dash and then covered with rolls of electrical tape is a daunting procedure.

[Hey_jude]

Thank you for your response.  I chose to replace the turn signal switch this winter and that area is very tight.  I'll pull it and look deeper into it.  The fan switch is still a mystery as well.  where does the ground for the fan switch run? Any thoughts on this?

THanks.