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Discussion Starter #1
Have a 06 zx5 that has developed a battery drain issue when the car sits. Seems to be find as long as driven daily, but if it sits for over a day sometimes battery won't have enough juice to turn starter over. I say sometimes cause there are times when car has sat for 2-3 days and started just fine. Batt is around 3 months old and i've had it tested at two different places, passed as good both times.

Testing with my meter when car will start, bat sits around 12.8v with key off. With car running is at 14v with nothing on, around 13.2 with all accessories and lights on. Connections appear to be good and no cel or bat lights staying on in dash . I have checked bat terminals with meter during the times when car would'nt start and voltage would show around 7.5 to 9 volts.

Next i hooked meter in series on neg side of bat to look for parasitic draw. Here's where i'am not sure whats going on. When i first connect meter thereby completing the circut, i get a .89 amp draw but just for a few seconds then it quickly drops to .01 amp and stays there. (This on the 10 amp scale on meter.) Admittedly i'am not real knowledgable with more modern cars loaded with electronics to know if what my meter is showing is normal for this model. I did go ahead and started pulling fuses from engine compartment box to see if anything changed on my readings, no effect.

Disconnected main hot from alternator which also had no effect on meter readings. However if i connected a test light inbetween main hot and alternator the light will flicker on and off which on a older car would indicate and open circut/ bad diode in the alt. On the focus though it is my understanding the the alternator is connected to the pcm so not sure if this would effect the test light method in anyway.

Where to go from here? Anyone with opinion on whats going on or what i should check out next? I just know something an't right, bat should'nt go flat after sitting just a few days and do it radomly to boot.

flames
 

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Discussion Starter #2
After short drive last night i checked voltage across terminal with car off, was at 12.8. Checked it again in afternoon today and voltage was at 12.5, i was expecting to see lower given the time it sat. Makes me think have intermitent short somewhere. Did discover that sometimes the third brake light works and sometimes it don't. After what i've read about the hatch wiring going bad i'am hoping this may be the source of my problem.

Only thing i wonder about is that if that wire harness shorts occassionaly bad enough to kill the battery, should'nt i have some blown fuses?
 

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Hatch wiring could be a possibility considering how intermittent your problem sounds to be.

Wouldn't blow a fuse unless something shorts to ground, if it would short to something that would apply a load it would just use up battery power.

Double check if the brake light circuit is "live" on yours when the car is off, if so a short from that could be an intermittent drain.
 

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Discussion Starter #4
Update

Finally got a little time to tinker on the focus and decided to check out the hatch wiring. Here's what i found


Got two wires with bare spots right next to each other, these need to be fixed even if not related to my current problem. So i was off to parts house for wiring supplies before they closed and by time i got back i was out of daylight. Going to check tomorrow if any of those wires are "live" with key-off and then repair damaged wiring. If they turn out to not be "live" then i guess i'll have to keep searching for source of my problem.
 

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Discussion Starter #6
Gremlins crushed, for now anyway

Well the wires that had bare spots were not live with key off. Repaired them and 3rd brake light works ALL the time now and according to my wife(her car) the problem with cruise randomly shutting off has gone away. Don't think that this issue was causing bat drain while setting but may have contributed to alternator damage.

2nd thing discovered while using a more accurate meter was that the cig lighter was cause small drain with key-off, replaced socket. With old socket in, meter would show 100ma draw on bat with key-off. Now shows 20ma draw with key-off with new socket.

3rd thing was discovered when i removed alternator and had it bench tested at parts house. While voltage output was fine, amperage was well below spec. Effectively the alt functioned more like a trickle charger than an alternator. Been a week or so of cold weather, short trips at low speed with lights one and car setting for couple a days in between. Have had no further issues with low battery problems. Think we're good for now[cool]
 

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Nice fixin'!

Got a few problems sorted out.
 
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