What could cause the PCM to spontaneously drain a battery and then start smoking when powered back up?

Sunday the truck is fine. Saturday the battery is stone dead. I hook up the smart charger and it says "Error". I double check connections and it still says "Error". I figure I'm smarter than a smart charger so I hook up the old stand-by jump starter and set to it "charge". Hood light comes on, I open the door and all the interior lights come on then I see smoke coming from the battery corner! I immediately unhook the charger.

So now I'm thinking maybe the smart charger is smarter than me and my battery is bad. So I swap batteries with a good deep cycle. As soon as I start to connect the posts smoke starts again from the PCM. Do they just finally give up & go bad? I'm familiar with failing ones that cause loose of features but to apparently just short circuit itself?

I've gone over and over in my mind what I could have done/changed over the weekend (I had a productive, until this, truck love weekend prepping for Indy). Nothing electrical and nothing that could have pinched or cut a wire. What gives???

 

For those of youall that have experienced a failed PCM, was there smoke involved when it happened? Like, is that the normal way they go?

 

They say the smoke is the magic that makes a PCM work... once it's out, there isn't any magic left.

My son's PCM went on his dakota- different beast I know, but it bit the big one from failed solder runs. Half the truck worked, half didn't, and it went all at once. We found a rebuilt one online that wasn't too bad, it worked great. Guy even loaded the miles and vin on it before he shipped it to us.

Sorry you're having issues, I know this is a big pain in the rear.

 

My plan it to test the alternator first. Then I plan to put the battery back in and then hook it up just to see if everything not PCM controlled seems normal. Then I'll hot wire the FSS, start it and see how everything behaves.

 

I like that thought.

My alternator tested bad so either it went and smoked the PCM or vice-versa. I’ll do some testing and see what I can find out.

 

Ok, good luck. Let us know how it goes and what you find out about the PCM.