P0720 and dead battery
I just replaced my batteries less than six months ago. The batteries that I had in the truck were only a year old and were replaced under warranty because they failed. I did some basic electrical tests to check for amp draw with the key off, charging voltage, etc., but found nothing of real concern, so I assumed I just got bad batteries the last time around. During a recent blizzard here in Northern VA, I was out in 4WD high and as I was cruising down the road, the truck stuttered for about 5 seconds and the engine cut off. I immediately tried to restart it and my starter solenoid started to click. I finally got a jump from a firefighter in a Suburban with an HD charging system and dual batteries and I got my *** home as fast as I could, where it began to stutter again just as I pulled into my spot. At this time it was in 4WD low, the SES light was on, and the O/D light was flashing. I shut it off and let it get snowed in. A week later, I went to move the truck and the batteries were so dead it wouldn't even chatter the solenoid. I got it jumped again, took it out of 4WD (in neutral) and then engaged reverse. When I pressed the throttle, it made a whirring sound like it wasn't fully engaged in gear. It almost sounded like a REALLY bad P/S pump. I put it back in park, then back to R and it moved fine. Let it idle for about 30 minutes after I moved it so it could charge. During that time I checked codes and got a P0720. Truck didn't move for another 2 days. Went to start it again and it was dead. I've heard of the OSS causing problems due to RF interference from a bad alternator, but I can't help but think that there may be more than one problem (due to my tranny/4WD behavior). I know on some Explorers people have had problems directly linking the electronic 4WD and the OSS. If anyone has any ideas or has had a similar problem, please let me know. Thanks!