I've had problems with my battery going dead after a few days of my '98 Explorer XLT sitting in the garage. There's door light or anything else I can see that is a problem. I replaced the battery because I thought that may not be holding a charge. That is not the problem. How can I test to see where the juice is leaking from. Any help is much appreciated.

 

Do you have a multimeter with an ammeter function, or do you have a 12 volt test light?

 

Easiest way is with an ammeter. Hook it up to the battery. If there is more then a .25 amp draw, there's a problem. Start pulling fuses until the draw goes below .25 amps. Then troubleshoot the circuit that had the current draw.

 

Poor-mans way is to disconnect any one of the battery terminals (just one) and place a test light between the terminal and the battery post. With all the doors closed, power off, etc. does the test light illuminate? If you have a radio that draws a little to keep your presets, or an alarm, you may have a small glow to the light which is probably normal. If the test light glows brightly, then you have a strong battery bleed somewhere. Start pulling fuses until you isolate the circuit the draw is coming from. Once isolated, the bright glow will go out. If you find no problems, check your charging system. Interpreting the brightness of the light is the key. Try your test light directly across your battery terminals first to see how bright it can get.

Don't discount the battery just because it's new. I've bought (and sold) plenty that were bad off the shelf. Have it tested.

 

The test light procedure used to work on older cars, but newer cars you can't count on it. You may have a draw but not enough amperage to light your test light. Also most newer vehicles do have a draw for quite a bit of time (30-45 minutes) after the key is turned off. Here's what you do.

Loosen but do not disconnect the negative battery cable.

Start engine up, allow it to reach normal operating temperature... shift through the gears.. then shut if off. Remove keys completely from ignition and make sure all doors are closed and lights are off.

Hook up the contacts of your ammeter the the negative battery post and the battery terminal. Without opening the circuit, remove the battery cable while your ammeter is connected, you should see an electrical load in the range of 0.50 to 1.00 amps (possibly more).

Go have a sandwich or something and wait an hour. This gives all the modules and computers time to go to "sleep".

Come back and observe your reading. If it is below 0.030 you have no parasitic draw. If it is above 0.030 (especially about 0.100) you DO have a parasitic draw and start pulling fuses one at a time until it drops down. It is possible you have a relay sticking in one of the modules, possible the BCM, preventing it from going to sleep and staying powered up all the time.

Good luck.