Gmtech, I think I read the question better than you did. And I'm not "trashing" your response. We're all adding comments when appropriate. You're the first person to be offended by someone else jumping in. Get used to it. When I'm wrong, you have nothing to worry about. When you're wrong, there's no need to feel defensive.
"recently the battery began draining for no apparent reason until it finally died and had to be replaced."
At this point all we know is the battery could have been defective and there was no other problem.
"I purchased a new battery and had an AVR test done to determine if there was anything drawing power from the battery when the car is not running. The AVR test came back negative so I put the new battery in the car."
"AVR" stands for amps, volts, resistance" which is very misleading and uninformative. I suspect the mechanic used incorrect terminology, but it's irrelevant. "So I put the new battery in the car" implies a drain test was done and by "negative", no drain was found.
"Everything was fine for a few days, "
If there's a drain, why didn't it cause a problem for a few days? In fact, that's exactly how a dead charging system acts. The engine will start and run fine on just the battery, especially a new one, until it runs down in a few days. Since so many things are controlled by computers, they may not turn on at all with the low voltage even though the battery isn't totally dead. The entire instrument cluster is a computer module, so it stands to reason it would not turn on at all if the battery voltage was merely low. Of course that gives the appearance of being totally dead. There is no indication a charging test was performed. That COULD be what was meant by "AVR" test, but then why were there no results mentioned?
What we haven't heard yet is whether a jump-start brought the car back to life and if the battery runs down while driving. If it started fine for a few days, that suggests there isn't a drain or it's so small, the battery had plenty of time to recharge while driving the next day. That isn't likely to suddenly change.
The description still sounds like a charging problem, not a drain. That's why I suggested the battery voltage test as the place to start. It's easy, fast, and will tell in a matter of seconds if I'm right or we need to look for something less common. Worn brushes are extremely common in the Nippendenso alternators, and they're rather easy and inexpensive to replace. They can be intermittent too for weeks or months before they fail completely. Watching the charging gauge will identify when the problem is occurring, but not everyone, including me, does that continually.
As for disconnecting modules that haven't gone to sleep mode, that is extremely unprofessional. Who wants kick panels and inner fender liners pulled apart, assuming you even know for sure which modules are involved and one of them isn't the cause of the problem. The industry standard procedure is to remove a battery cable, insert a jumper wire, then insert the ammeter, wait a half hour for the computers to power down, then remove the jumper wire. If the meter scale needs to be changed, the jumper wire must be reconnected first. If a computer isn't shutting down, you want to see it in the meter reading. You won't if it's unplugged.
Chrysler had computers that needed to time out at least as far back as 1997, and possibly as far back as the 1995 model cars. I left the dealership in '99 and we had already been following the special drain testing procedures for years. You can even hear the Engine Computer "sing" for 20 minutes in front of the left front tire on the '97 Stratus. No one expects a mechanic to memorize which computers on which models in which years need to time out. We just automatically follow the same procedure and wait a half hour. Even if you knew which computers to unplug, it would take longer than a half hour to get to all of them. Then you have to reassemble everything when you're done.
If you follow any of my other replies, you will see there are a bunch of people adding their comments after mine. They might bring up something I didn't think about, or they might point out something I overlooked, and a few people even love to tell me I'm wrong. I did make a mistake once, (a long time ago), and I might make another one some day. Thank goodness there's other experts here to check up on me. Adding comments and corrections is done for the benefit of the person trying to fix their car, and there's no reason to get hostile or defensive or to feel offended. I never said your answer was wrong. There are a few other people who post some really off-the-wall suggestions, but I just let their ignorance speak for itself. I don't have to add anything to their replies. You just keep doing what you're doing and don't take offense when someone adds another reply. You are welcome to add to mine too when appropriate.
The reason I jumped in on this one is I'm a Chrysler expert, a Chrysler radio expert, and an electronics expert. I only know three things, and this post covers them all.
Thursday, August 18th, 2011 AT 6:23 AM