Need help: Battery Drain

[jfletchall98]

I have a 02 LS v8. It is currently having a battery drain issue. I did some reading online and learned that some of the electronic modules stay on after you turn the car off and get out. Everything I read said that the computers need about 850mA while they are awake and should drop down to 35mA in shutdown mode after about 45 minutes. Any door opening, key fob command, trunk or hood opening, etc would wake the system back up making it pull 850mA for another 45 minutes or so. With that in mind I hooked my multi meter up so I could see the amperage being drawn from the battery. At first it spiked up to about 1200mA then within a few minutes dropped on its own to about 900mA which is supposed to be normal. I came back and checked it 43 minutes later and it was pulling 26mA, pretty much business as usual. I sat and watched it for about 3 minutes when suddenly it jumped back up to 1200mA then back down to 900mA. I came back around 40 minutes later and it was back down to 26mA. Then about 8 minutes later it jumped back up again. So for some reason the computer is waking itself back up. Not sure if one of the modules is bad or what. I don't really know what to do next. Has anyone dealt with this before? Really just needing some advice on how to diognose this further. Any help or ideas would be appreciated, thanks for your guys time.

 

[joegr]

Try it again, but with all the doors open and the hood and trunk open. You'll need a meter that can handle a few amps due to the light bulbs.

If it now stays asleep, then you can shut doors and hoods one by one to see which switch it is. I'd bet on the hood switch.

On the other hand, if this doesn't allow it to stay asleep, you'll need to dig a lot deeper, which often requires a dealer level scan tool.

 

[jfletchall98]

When I did it the first time I had all the doors, hood, and trunk open but I had all of the little switches taped shut so the car thought they were shut. I checked all of them after and none of them moved so that wouldn't be the reason it woke up. Car has kinda had electrical issues in general. Like for example the power locks only work on the driver front door. It's got a door seal leaking on the front driver door. Leaks right down into that pocket in the door panel. Got it sealed up now but if did fill up with water a few times.

 

[jerrym3]

My TBird had a problem with the AC control head. Took Ford months to find an OEM replacement in Mexico.

 

[joegr]

Well, it could be the FEM or any of several other things. Your test with the switches taped down was not valid. That does not simulate the true position of the switches, and it leaves dirty switch contacts in play.

 

[jfletchall98]

Hopefully I'll get a chance to try it again tomorrow, I'll try all the doors shut and everything. Once it's sleeping opening the doors should cause it to wake up right?

 

[joegr]

Hopefully I'll get a chance to try it again tomorrow, I'll try all the doors shut and everything. Once it's sleeping opening the doors should cause it to wake up right?

No, start the test with everything open, and leave it open. It will still go to sleep. If it remains asleep for a long period of time, you can then shut things one by one. After each one, wait for it to go back to sleep, then verify that it stays that way for a long time. If it starts going in and out of sleep after you shut one, you have found a bad switch. If it goes in and out of sleep with everything open, then it's very unlikely to be a switch.