While replacing the headlight switch to my 1993 Ford F350 (7.3 diesel), I followed the instructions to “disconnect the negative battery cable”. Unfortunately because this truck has TWO batteries wired in parallel, and I only disconnected one of them. One of the next steps was to put the column shifter in its lowest position, so I had to put the key in and turn to the accessory position to unlock the shifter. As soon as I turned the key, I saw a puff of smoke come out of the steering column and quickly turned it off. It could not have been on for more than a few seconds. After disconnecting the other negative cable, I completed the replacement of the headlight switch, reconnected the batteries, threw a fire extinguisher in the cab, and turned the key expecting the worst. To my pleasant surprise, it started right up, and drove just fine. I tried out the headlights, instrument cluster illumination, blinkers, hazard lights, wipers, overdrive switch, fuel tank switch, and everything appeared to work normally. The main things I am wondering now are: what caused the smoke to appear, what’s the likely source of the smoke (did I cook something important, or maybe just a little insulation/tape?), and should I be concerned that something could happen down the road as a result of this mishap? If so, what should I be on the lookout for? Thanks in advance!
The time to have looked for “cooked” pieces and things was when it was all apart. Now you will likely find the part/piece when something fails.
Damage, yes. Wiring overheated and quickly. Something melted and likely shorted out. What was it? So many wires in that area and so little space to see anything. When you find something that doesn’t work you’ll know the circut that was affected. You’ve got wipers, washer, turn signals, high beams, and more all running wiring through there.
I agree with the previous answers. Normally…I would tear the steering column apart to search for the smoked wires/part. Since there are too many possibilities in this case it’s probably best to wait and see what fails. If it smokes again I would disconnect both batteries and tow the truck to a good mechanic.
Thanks to all of you for your quick replies. It is a mess of wires back there, but fortunately the dashboard and steering column trim is relatively easy to pull off. I will do a more extensive check of all the functionality, and probably dig into the wires in the coming weeks (it is not my daily driver), since just because the truck worked now, probably doesn’t mean something couldn’t happen weeks or months later, correct?
Just to post my solution, in case someone has a similar problem: I tracked the problem down after doing some more research online. It turns out that the specific problem is a somewhat common one - the insulation on the wire for the Overdrive on/off switch had frayed, and it was grounding itself on the shift column. I used a punch to remove the pin that holds the automatic transmission shift lever in place, wrapped some electrical tape around that wire, and that electrical problem is gone! I’m guessing that the insulation has been gone for a while, but my little incident with turning the truck on with only one battery connected exacerbated the issue.
Thanks for posting back and clearing this thread…Few bother to do that…