99 Taurus electrical problem

My wife's car is a '99 Taurus LX and it's been sucking the battery dry after a day of non-use. I just put in a new battery and alternator, but there's still the same problem. The shop I brought it to ran a Vat40 test and showed that that battery, starter, and alternator are all fine and that there was only a draw of .029 Ma. I got home put my 12 volt test light on the battery and found that the light lit up bright until I pulled out the MAXI fuse in slot one in the underhood fuse panel. Then the light goes out completely, but I lose my radio, trunk release, dome light, cigarette lighter and lord knows what else. I'm now stuck and need to know where to go from here.

Suggestions?

My wife's car is a '99 Taurus LX and it's been sucking the battery dry after a day of non-use. I just put in a new battery and alternator, but there's still the same problem. The shop I brought it to ran a Vat40 test and showed that that battery, starter, and alternator are all fine and that there was only a draw of .029 Ma. I got home put my 12 volt test light on the battery and found that the light lit up bright until I pulled out the MAXI fuse in slot one in the underhood fuse panel. Then the light goes out completely, but I lose my radio, trunk release, dome light, cigarette lighter and lord knows what else. I'm now stuck and need to know where to go from here.

Suggestions?

I'm in a nit picky mood tonight. I assume you meant that the Vat40 test showed a current draw of 29 milliAmps, or 0.029 Amp. A draw of 0.029 mA would not be enough to even allow the radio or clock to maintain presets or time. Also, I assume you disconnected one of the battery cables and put the test light in series with it and the battery.

Sorry, just felt like picking on you I guess. Is the Maxi fuse in slot one the 40 amp fuse? If so, it appears that that fuse applies power to the Generic Electronic Module, the Multi-Function Switch, the Passive Anti-Theft System (PATS), Remote Anti-Theft Personality (RAP) module, and the instrument cluster to name a few items. These modules are all controlled by fuses inside the cabin, it looks like fuses 21 (cigar lighter), 22 (power mirror, power antenna, trunk light), 23 (GEM, RAP, and PATS), 24 (Instrument cluster), 25 (OBD-II data link connector), 26 (power trunk release), 28 (Cruise control deactivate and brake pedal position switch), and 29 (multifunction switch). I guess I'd suggest you continue on your path of pulling those fuses and seeing which fuse or fuses it takes to keep your light from glowing brightly.

I should also mention that the above information is taken from the service manual for a 1998 Taurus, so it may not match up exactly. I bet it is very similar though.

Good luck,

-Rod

I've since found that buy putting maxi fuse one back in and pulling the radio fuse, the light on my 12V tester is very dim. So is it just a loose wire on the radio?

I've since found that buy putting maxi fuse one back in and pulling the radio fuse, the light on my 12V tester is very dim. So is it just a loose wire on the radio?

Sorry for the slow reply. I've been on vacation for the past week, away from phones and the Internet.

Well, to say for sure if the radio is the problem, you really need to use a current meter rather than your test light. With the test light, you cannot tell how much current draw is required to light the light. The radio will draw some current to retain the clock setting and radio station presets, etc. If your car is really drawing 29 milliamperes, that should not be enough to run a good battery down in any reasonable amount of time (would take months rather than days). Any yes, 29 mA may be enough to light your test light, although I would not expect it to light very brightly, unless it uses an LED rather than a bulb.

If the current draw is more than 70 mA or so, I would suspect that you have something drawing an excess amount of current. To drain a good battery enough that it wouldn't start the car after sitting a day, you'd need a few amps of current draw (1000 mA to one A). I wouldn't expect a bad trunk light or glovebox light to kill a good battery in a day.

You didn't happen to get your battery from Autozone did you? I have good luck with most batteries from there, but I did end up with two for my previous Nissan Pathfinder that would not start the truck if it sat for 3 days. I verified that I had no current draw, had them test the charging system and battery, everything checked out fine. Still, after three days of sitting, the thing wouldn't start. Finally got them to warranty the battery (6 months old) after I showed them a data log of my Fluke 867B meter in series with the battery. After 2 week, same thing with the new battery. Decided to get an Interstate battery, never had the problem again.

I've used Autozone batteries in other cars and never had troubles, so I cannot condemn their batteries. Maybe they just had a problem with a lot or so of that battery family.

-Rod