All, I got a P0300 misfire code this morning on my way to work. I was close enough to work that I got into the parking lot, and immediately felt like an idiot when I popped the hood because I saw I hadn't refitted one of my plug wires back onto the plug last night. It was just hanging there beside the exhaust. Refitted it, however the car wouldn't start back up after I turned it off. It won't turn over, no lights on the dash, no electricals at all. I'm sure the plug wire was the cause of the P0300 code, but what are the chances that I fried something during the drive? I'm going to go back down during lunch and check battery voltage.

 

Update: jumped it over lunch which worked, just haven't driven it around to see if it will build up and hold a charge. So I'm thinking at worst I need a new battery, possibly the alternator. Still not sure though how that might be related to the misfire..

 

Check your battery cable terminals and ground terminal at alternator bracket. Maybe the misfiring/rough running caused the cable terminals to become loose.

lf alternator was failing, you should have got a light on the dash, indicating no charging.

How old is battery, anything over 5/6 years old has probably seen its better days.

 

The battery terminals are good - the tester at the auto store said the alternator had gone, but I will check the ground terminal there before swapping anything! I didn't get a light (I'm assuming the battery symbol in the owners manual?). I did get an intermittent warning chime but none of the audible warning descriptions sounded like the one I got..
Battery was from P/O so you're right it could probably be replaced either way.
Thanks!

 

These trucks are notoriously finicky with low voltage and batteries. I would not buy an alternator until you swap in a new battery.

 

Good to know, I'll swap in a spare before hand.

 

So I swapped in my wife's battery and drove it around for a little while - no noticeable signs the alternator was bad like dimming lights, electricals getting brighter or dimmer depending RPM's, and the battery was reading 14.2 with it running (at the end of the short drive though it was ~13.9). Oreilly's was on my way home so I went ahead and picked up the new alternator but I'll just leave it in my passenger seat and see if I need it this week. If not I will return it or keep it as a spare!

 

If it started with a different battery...it sounds like you found your problem.

 

Well, my battery was very dead originally, but I used a battery tender to bring it back up to full charge, and I've been driving around for a day and a half with the old battery back in the car, without any signs it isn't holding charge. So my hypothesis is that somehow I drained the battery but not beyond repair. If it starts having issues again I figured I'll replace the battery at that point