'02 - Ford Windstar - Battery Drain

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I need help from the Ford guys... We have been given a '02 Ford Windstar with 276K KM on it. It is equipped with the 3.8L V6 and runs great. We have tested the charging system and the alternator is good, and the battery has been replaced with a new one which passes the test hooked up to a diagnostic machine. (We even tried an alternate, battery that is known to be good just as a double check) All electrical connections and grounds have been serviced and tightened as a double check. The problem we have is that when we replace one of the main fuses it causes the battery to drain overnight. When the fuse is removed the battery will be fine and the van will start fine. Does anyone know what a common problem with these vans might be? We have checked the door-lock control module which is a common problem from what we have read and it checks out. It isn't one of the things on this main fuse line that is being disabled when we pull the fuse so we know it's not that. Thoughts? Steve
 
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My 98 Taurus seems to drain down the battery but not in day. It takes about a week or so. A lot of library's have a way that you can access TSBs. You then would look under electrical and might find your exact problem that is addressed in one of the TSBs. I have never found the reason that my Taurus drains. If it drained overnight I would be much more motivated. Good luck.
 

StevieC

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That's why we started pulling fuses to try and isolate it to one circuit. Something on that main bus fuse as I posted above is creating the drain and I'm hoping a Ford guy or someone that works at a dealership or has experiences with these vans can tell me where to look. My dad is a mechanic so all the obvious things have been checked but we need a wiring diagram to pinpoint it further and Ford wants big $$$ and Haynes manuals aren't the greatest for this van as we had borrowed one from someone and it's very vague.
 
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That 50-amp fuse most likely feeds another fusebox, maybe the underdash one. Sometimes the underdash fusebox had TWO fuses feeding it. And..sometimes...the underhood fusebox is fed by a main fuse in the same box. I suggest getting an ammeter and start pulling other fuses.
 
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Ditto on the ammeter and pulling interior fuses. Hook up the ammeter, give the car 15 minutes to let all of the modules go to "sleep" then start pulling fuses. Simple stuff like glove box lights/switches are a good place to look first. Radios are another semi-common problem as well. See if it stays warm when with the key off.
 
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 Originally Posted By: punisher
Ditto on the ammeter and pulling interior fuses. Hook up the ammeter, give the car 15 minutes to let all of the modules go to "sleep" then start pulling fuses. Simple stuff like glove box lights/switches are a good place to look first. Radios are another semi-common problem as well. See if it stays warm when with the key off.
Ditto on this. It can be time consuming but is usually the best way to find something.
 
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StevieC

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We will be doing this tomorrow... Raining here today and it's late in the day with so many fuses to check.
 
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One other thing I thought of. I haven't messed with one of those vehicle in a while so I can't remember exactly where the cable for the alternator connects but I've seen bad doides in a working alternator drain a system.
 
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Not from what I remember. Like I said, it's been quite a while (severasl years) so my memory may be a little off. The easiest way to check is to just pop the + wire & electrical connector off the alternator and see if it changes anything. Then check with the connector on and + cable off, then vice versa.
 
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Bad alternator diodes will draw even with the key off. I would have suggested that but I didn't think the main alt output runs through that fuse. You can also check a bad alt diode by the "warm" test as well. Cold engine+warm alt= diode problem. You can also turn your DVOM to "AC" and measure AC current at the battery with engine running to find faulty diodes.
 

StevieC

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Had a break in the rain... It's not the alternator diodes. We have it nailed down to this... If we pull the fuse that supplies power to the inside of the vehicle then the battery doesn't have a draw. So something inside is causing it. We are going to nail what it is tomorrow buy pulling all the inside fuses/relays from the box under the dash and replacing one at a time until we catch the bugger that's causing the grief. Then we will know where to look.
 

StevieC

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Well now we seem to have run into another problem. The anti-theft has locked us out from starting the vehicle because it would seem the transponder in the key went bad and we only have the 1 key. According to Ford you have to have it towed to them to have a new key programmed in if you don't have another working one. So my dad is currently making arrangements to have this done, then we will continue sorting out the drain. I will keep you posted... \:\!
 
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 Originally Posted By: punisher
Bad alternator diodes will draw even with the key off.
A clue that this might be the case is when the car's been sitting parked for hours and the alternator is the warmest thing under the hood...
 
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