Down the rabbit hole...can't shut the engine OFF
Lord, I hope that this is a stupid question.
I acquired an '01 Intrepid that was maintained to death by the PO, my best friend's father (a retired engineer). Even though it has a 2.7 it runs perfectly. Have had it a couple months with zero mechanical problems. I have been repairing some collision damage, but none of it has caused any issues with any systems.
Today, I decided to removed the Sony CD changer, which involved pulling the console cover over the shifter (to get to the radio console). I could not remove it entirely due to how the shift lever & its leather boot are installed, so I horsed it out of the way & finished the job. This did involve occasionally moving the shifter back & forth to get at screws, etc.
After an uneventful reassembly, I found that the battery was nearly dead (clicked on trying to start, but had enough juice for lights) . I have known that the battery was dying since I got the car - was going to change it out this spring. Deciding to charge the battery, I found I could not remove the key from the ignition. I eventually figured out that the horsing of the shift console caused the leather boot to bunch up in a way that prevented the lever from being completely seated in the Park detent. However, that knowledge came later. I eventually wrestled the shifter fully into Park & got the key out of the ignition, set up the charger & left it alone for 4-hours.
On return, I entered the car & it started right up. I shut it off, and couldn't get the key out. After about a half hour, I sorted the console issue, and the key/ignition block behaved normally. I removed the battery charger & put it away, and left the car.
About an hour later, after sunset, I happened to look out my kitchen window & noticed that the instrument lights were on - as though the car were running. I found the car not running, no key in it, but the dash lights were on.
This is when I went down the rabbit hole - there was no way to turn them off. Returning with the key, I started the car without any issue or weirdness. I turned the key to the off position & removed it. The car remained running & the dash lights stayed on. I cycled the key /ignition switch every which way, but nothing happened. WTF.
I cycled the ignition off, and removed the key (dash/instrument lights burning), and pondered what to do next. Within 20-seconds, the engine began to run rough, stumble, then died. Dash lights stayed on. I started it again, then cycled the ignition off, and removed the key; died the same way: within 20-seconds.
Totally confused, I searched online & found only that there is a cutoff relay that, if removed, kills the engine. Tried this and it worked. Instrument lights stayed on.
Next advice: maybe that relay's bad. Switch it out. Nope; no change.
The only other advice was to disconnect the battery, wait a half-hour, and reconnect it. No change. Tried it twice., second time, over an hour. I did note that there was a lot of sparking when I reconnected the neg batteery line - as if there was something drawing a fair bit of current - and I could also hear a faint, anemic buzzy whining that stopped & started depending on whether or not the battery was connected. None of the fuses are blown. I could not trace this noise. Perhaps it's the fuel pump?
My only conclusion is that I somehow porked the ECU when I charged it. This car has never had a day's trouble in the past three years, and no issues since I bought it two months ago. It's been boringly dependable.
I have lately been told that it may be the ignition switch - although I would consider this a cosmic coincidence, given that there hasn't been a single instance of the electrics acting up prior to this afternoon.