Hi Mustang. There are many possible explinations as to why your EEC recently went to the great EEC graveyard in the sky...
1. Manufacturing defect
2. ESD discharge event
3. Thermal fatigue failure
4. Vibration fatigue failure
5. Component failure on the EEC board.
Automotive electronics is designed to be very reliable and robust. It must survive the harshest environments including thermal and vibration.
My bets are items 5, 4, 3, 2,1 (in that order).
Many modern active semicondustor devices are produced with the human discharge model in mind. This means they use snubber devices to prevent damage to their devices from ESD events. In fact, automotive semiconductor IC's are designed to survive a reverse 2x voltage bias. Imagine connceting 2 (12 volt) batteries in series and then connecting the EEC + and - wire on backwards (24 volts!). But, unfortunately, not all devices in the EEC can withstand that (tantalum caps, electrolytic caps, FET's etc).
As far as the ESD event your the winter is the worst. Atmosphereic moisture levels are low when it gets very cold, this drives up the discharge potential. The only way to protect your car would be to keep it at the same potential as Earth ground. You would have to connect a drag chain to the car to discharge the electron buildup. The problem is in the tires...they insulate you from the earth ground. Then you get into the car on a cold day, rub your ass on synthetic seats, pick up 10,000 volts (or more). Get out of the car, put your foot on the ground and close the door. ZAP! ESD event. Shake your hand vigorously and say a few curse words.
sorry for the ramblings...I'm and Manufacturing Engineer....and rarely get to talk about subjects I know anything about on the board....