99 EX Sport 4.0 4X4 intermittent battery drain

[Blueraven]

I read another post about fuse 15 caused charging problems. The thread also stated that ford uses the battery lamp in the dash as a circuit protector for the charging system and if the lamp goes out the battery will not charge. My lamp is not out, but I did reset fuse 15. I can't believe ford would be this stupid, but being a lifelong Mopar guy, I'm certainly familiar with manufacturers doing stupid stuff.

I'm still probably going to pull the alternator out this weekend and I might even snag a used regulator from the junk yard while I'm there.

Blueraven

 

[Schlarb55]

i have a 98 explorer xlt 4wd (old hospital truck some equipment still in it) and its having the same issues with the starting and keeping a charge. this is my 1st explorer (before that f-150s and mini-van) worked great in the snow and ice. in addition to the drain my PATs system seems to quit working properly. one time it works. next panic. nothing. and keeps going on with no real pattern. the battery is old and need to get a new 1 so atm i have been disconnecting the battery till i need to go somewhere.

 

[Schlarb55]

I charged the battery and left is disconnected. battery is fine. so at work i swaped the rear defrost relay and the power relay. if thats not it next will be the alt. so hoping its the relay

 

[Schlarb55]

was the relay. so new relay friday. No troubles so far. thanks for the help.

 

[Blueraven]

well there hasn't been post on this subject for a couple of months and I don't want to leave this thread hanging, however since the weather has warmed up the problem has gone away. Looks like I'll have to wait until next winter to start troubleshooting again.

Blueraven

 

[Blueraven]

Well the problem came back with a vengeance. The good thing is the vehicle wouldn't start at all unless it was jumped. After it ran for a few minutes it would start on it's own, however a few hours later it wouldn't start without help.

I determined that the 6 month old battery was dead. I figure this was probable due to the constant drain and charge condition it had been experiencing. So I decide to do some more troubleshooting.

I've suspected that the alternator/volt. reg was bad but just haven't got around to having it checked. Well I pulled the alternator (only took 15 minutes) and had it tested. It tested good, however I still had my doubts so I went down to the local junk yard and pulled a used one. We'll after putting in a new battery and used alternator, the truck has been starting flawlessly for over a week now. I don't think it's started everyday for a week in 8 months.

Anyway, since the alternator was output the correct voltage, I can only assume that the internal voltage regulator was bad.

Thanks everyone for all the advice on this issue.

Blueraven

 

[grayghost]

I just searched this forum tonight and found this thread which is my exact problem. Just like Blueraven, 99 Explorer sport, battery intermittently dying. It started 6 months ago while my son had it away at college. He first tried replacing the battery which seemed to settle the problem for a little while but if it sat for 3 or more days the battery voltage would be too low to start.

We've spent the last month troubleshooting the problem. several times I've disconnected the battery and put a current meter in series looking for obvious current draw. We swapped the battery again, swapped the alternator, problem still there.

Last week on one of the 100 degree days it needed to be jumped 3 times. later that night is started fine...

Last weekend I disconnected the battery and again put a current meter in series and a voltmeter across the battery and monitored it several times day for about 4 days. the battery voltage varied but ended up settling around 10.5.

I have not replaced any relays yet, mainly because I don't know where to begin.

I'm a pretty savy car guy and a electrical engineer/technician by trade and typically love chasing electrical problems but this one seems to be a tough one.

If anyone can add to the list of probable causes I would sure appreciate it. Blueraven, keep us updated.

Thanks Pete

 

[Blueraven]

Go to the junk yard and get and used Alternator. If it doesn't fix your problem it only cost a few dollars, an hour of time and you have a backup Alternator.

Since I swapped the alternator 7 weeks ago, the vehicle hasn't failed to start yet.

Blueraven

 

[osteologation]

Go to the junk yard and get and used Alternator. If it doesn't fix your problem it only cost a few dollars, an hour of time and you have a backup Alternator.

Since I swapped the alternator 7 weeks ago, the vehicle hasn't failed to start yet.

Blueraven

Had this same problem in a f250. For 2 years. It wasn't a dd so we installed a battery disconnect. Just disconnect it if you wernt going to drive it in the next few hours. Problem was the brand new alt we put on 2 years ago was bad from the get go. It managed to test as a bad diode.

 

[grayghost]

I've already swapped the alternator (we have 2 Explorers) but that doesn't mean they both dont have bad diodes. I will check it with an oscope the weekend.

Thanks for the replies, Blueraven keep me posted

 

[budwich]

I think if you have hooked up a ammeter to the battery and let your vehicle sit until "all" circuits go to "sleep" (gem is "happy")... then read the current draw. IF it isn't too large, you have a charge issue. IF it is too large, you have a "unhappy" circuit which needs attention thru some form of "this is the way we pull the fuse, pull the fuse, pull the fuse" until you isolate the offending circuit(s).

 

[grayghost]

Charging looks fine, 14 volts as soon as the engine starts. I've pulled every fuse and relay at least twice, problem is that the "unhappy" circuit hasn't fully shown itself long enough for me to track it down. Where is the GEM and could it be the cause of this problem?

 

[budwich]

you aren't looking for voltage... you are looking for current.

 

[grayghost]

Budwich, I believe what your saying is... if I have little or no current draw while it is in sleep mode (which is what I have) then I may have a charging issue. My point was that with engine running, alternator is outputting 14V which should be normal operation making me believe the charging system is OK. Once the engine is off, I disconnect the battery and connect a series current meter. Looks like I will have to continue this until something pops up, I was hoping to hear of a common problem that had been found to cause this.

 

[budwich]

Not sure that you actually understand or that I understand. Let me try another way. On some cars / vehicles, they have ammeters NOT voltmeters... why? Because, it provides a potential better "understanding" of what is happening to your charge ( and discharge) system. Further, when I said you have a "charge issue". I didn't say that it was your alternator (a good candidate), there are other components of charge... like the battery (including cells) and the wiring. You need to determine whether you have a "charging" issue or a "discharging" issue. So far, I don't think you can say anything either way... at least in terms of the information that you have posted. In terms of your testing, I certainly would NOT expect you to connect up a ammeter while your engine is running unless you have access to such "specialized and costly" equipment... so it is very unlikely that you can "rule out" your charging system... hence, you need to rule out the discharge system. Anyways, good luck...