Chrysler Repair: 2001 Town & Country: Battery drains overnight, chrysler town and country, fuse one


Question
I have a 2001 Chrysler Town and Country, and we've noticed for the last year, if we leave it for the weekend, the battery drains. We purchased a new battery and resolve to drive it everyday; however, recently, the battery has been draining overnight, so, the car won't start anymore.

The first mechanic that I took it to, replaced the alternator but the problem still hasn't gone away.
About 6 months ago, I replaced the battery, hoping that the issue will go away, but it hasn't.

The second mechanic measured the draw off the battery after he pulled each fuse one by one and concluded it was the Body Control Module (BCM). Problem is that the BCM costs at least $700 new, from the dealership and before I make this kind of investment, I want to be sure I know what the problem is.

Any help on this would be GREAT!

Thanks.

Answer
Hi Alvin,
While the mechanic identified, most likely, the fuse that is drawing a lot of current when the van is shut down, and that fuse probably does supply the BCM, I suspect that he drew the wrong conclusion. While the BCM does handle that current, in all likelihood the item(s) that actually improperly use that current that is being supplied by the fuse is the problem rather than the BCM itself. The BCM is a 'brain' that handles many current using devices, rather than drawing much current to operate itself. There are 4 fuses that supply power to and through the BCM: 14, 19, 20 and 24. You could remove those fuses overnight (but don't use the anti-theft system when you leave the van, secure by using the push-buttons only or if garaged leave it unsecured; then use the door key to re-enter if secured). Then see if the battery is still OK the next morning. If so, then the next night remove the same fuses except leave 19 and see what happens. Then the next night leave 19 and 20 and see what happens. Then the next night leave 19, 20 and 24 and see what happens. Then let me know when the battery drain happens, or if the battery still drains after the first night with all 4 fuses out. Once we find which of the BCM-related fuses is drawing the current we can go from there.
Alternatively, ask the mechanic which fuse he believes is drawing the excessive current and/or look at the repair order.
If you wanted to purchase a volt-ohm-ampmeter you can get to the bottom of the issue quickly of localizing which fuse is drawing too much. Then we examine what specific items draw on that fuse. I would prefer to send you the instruction from the shop manual as it is detailed, if you want to do that testing.
So either way, let me know how you want to proceed or go ahead with what I have suggested. I would not put $700 in a BCM unless you observed it yourself with an ampmeter to be the only possible explanation.
Roland