Parasitic battery drain/help me play Perry Mason.....

[Toploader]

So far so good....with battery hooked up and rear defog taken out, battery remains fully charged. Have new switch ready to go in, will just wait a few more days for giggles;-)

[Toploader]

Try the underhood light. It would switch on when the hood was closed and turn off when I opened it. The whole time I had assumed the bulb was dead.

I took that bulb out over ten years ago with the trunk bulb.

[L1011tristar17]

Try the underhood light. It would switch on when the hood was closed and turn off when I opened it. The whole time I had assumed the bulb was dead.

[Toploader]

Btw, the switch I removed had the following F0MoCo number:EOVB-19A328-A2B

The new one I have ready to go in is: EOAZ-18C621B

I have no idea why Ford changed numbers??

[Toploader]

So it was actually nice today in NYC Removed the rear defog switch from the dash, re-attached the neg battery cable and now will wait and see if the battery again goes dead. If it remains fully charged, then I will know its the de-fog rear grid switch. If it goes dead, then I will remove the wires to the alt for a week and come back and see if will start.

[Toploader]

Yes!...I was also told that the rear defog switch often goes bad due to temp change!..........go figure???

[87GrandMarq]

But one has to assume that 0.000.7 amp drain is a nonissue.

I had a near zero drain too. I could let it sit out 8 hours during the day and it would start right up. I could let it sit for 4 hours overnight and it would be completely dead. And I couldn’t trace the draw to anything. My guess is that the difference in temperature contributed somehow. Pretty much what I’m saying is don’t rule out the alternator, especially if everything else checks out.


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[Toploader]

But Tom, if I leave the neg cable off for about a week and then put it back on.....the car cranks and starts right up! Which seems to suggest that the battery itself is not at fault, and goes dead only when the neg cable is re-attached to permit the battery to go dead due to this mysterious parasitic drain.

[Mainemantom]

In the past month I have replaced FOUR batteries. Granted three of the four were 8-10 years old. The other was 5 years old. Before I replaced them I did the following tests myself.
1. Hydrometer test. In all the batteries the electrolyte condition was poor or failed.
2. Load test. Two passed, Two came back as weak.
3. Cell test. Two had a bad cell.
Just putting the info out since you said AAA jumped started the car however it would not restart later. What may seem to be an abnormal draw could be a weak/ bad battery.

[sly]

It should be. Nominal drain on the newer cars is about 0.1 to 0.3A. I do always check alternator charge cable for active current draw when there's a parasitic loss apparently happening. In fact, if you have a radio and clock, you should have more than 1mA drain. I know the boxes I've had always had at least 10mA drain happening. My aero (granted, it's nowhere near original at this point, but still) has about 100mA draw and I have no issues letting it sit for 2 weeks and it cranking up no problem. My Expedition is between 100 and 300 mA with all it's modules and same story. 3 weeks and it starts to get grumpy though it will start.

[Toploader]

I had a similar issue going on with my 09 p71 a few months back. I tried a draw test but nothing came back unusual. I had another alternator so I threw that on there and the problem has since disappeared. Food for thought.


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But one has to assume that 0.000.7 amp drain is a nonissue.

[87GrandMarq]

I had a similar issue going on with my 09 p71 a few months back. I tried a draw test but nothing came back unusual. I had another alternator so I threw that on there and the problem has since disappeared. Food for thought.


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[Toploader]

Tom before I order these consider the following:
At no time when testing for a parasitic drain over two hours did the meter go above the following:
0.0007 milliamp. Hate to just purchase parts without any definitive proof the parts are in fact defective.

[Toploader]

Tom I never thought of doing this, what the "H" I will see about ordering the three of them.
Thanks for the suggestion.

[Mainemantom]

Suggestion would be to replace the following. They are getting old.

1. Rear window defroster switch.
2. Door switches
3. glove box switch

I have had to replace all of those on at least one of the cars. Just replaced the defroster switch last week.