jim010

I have a 2012 GT automatic. I seem to have developed a power drain when the car is off. I hooked up a multi meter and I am reading a current of 0.6 amps when the car is shut off. Went pulling fuses and I think my issue is fuse #5 on the SJB. Current drops to 0.2 amps (that still high?)

Fuse 5 controls the shifter, headlights, interior lights, and looks like radio. as well as TPMS.

Fuse 25 also seemed to have an affect, but not much. Dropped to 0.4 amps when I pulled that one.

There are no lights left on that I can find. Not sure where to go from here. Suggestions welcome.

jim010

What is a normal draw for our cars anyway? 50 mA?

jim010

Anybody?

houtex

Hey, Jim. I didn't see the other ones. Gonna spew words, did a little legwork on it, maybe they'll help...

Lookin' around, it would seem 50mA is an acceptable norm for any sleeping car... but that was before toys got in 'em, like memory seats, active alarms and the like. Lincolns are supposed to be ok with 80mA, for example, because of all the STUFF in them. I wouldn't be surprised if that's the 'new norm' for the newer, fancier, more tech laden Mustangs. Also, it's kind of expected that they get driven a couple of times a week or so to keep the batteries from sulfating and dying. If you don't... well, there's that. Maintainers should be employed, or terminal disconnects, if the car isn't driven enough.

I've also read they can take something like up to 4 hours to sleep all the modules. But that was a Buick issue with the A/C in that case I read about. Still. Might need to wait overnight or something to get a good 'sleeping' reading?

Anyway, if you can get it down to 80 or less, then I'd say you're good. Anything above that, gotta find the thief.

Now, you say SJB Fuse 5 is pulled and that drops .4 out of the .6 drain. Good. But your list seems to conflict with Ford's. The only thing that fuse is there for is the transmission shifter and Field Effect Transistor (FET), not the headlights or such. What's an FET? It's a thing used by Ford in the SJB and the Body Control Module-B to measure voltage drops in circuits. And there's an FET on the shifter circuit in the SJB. Very interesting, they use a variable resistor setup to cause a voltage drop for the FET to then get measured by the microprocessor to know what gear you want. Weird, but ok, sure, guess that works... Bottom line there's two things there: Bad shifter selector switchgear, or a bad FET in the SJB. Disconnect the shifter and see what happens. Hopefully that stops the drop, and the shifter needs replacing (or the connectors need lookin' at...)

You also say the Fuse 25 was pulled and had a .2 drop. So all your drains seem to be now known out of the .6 total you spoke of. Yay and things!

But what does 25 do? You didn't specify which Box, although one can assume SJB given the previous mention regarding SJB Fuse 5 above. In the SJB, Fuse 25 is the inside trunk lamp, sun visor mirror lamps, and the entire overhead console. In the BJB (Battery Junction Box, engine compartment) 25 is the A/C clutch relay. Just gotta disconnect each one to see which it is. I'm betting the trunk lamp is on, probably a bad switch back there.

Just for grins, 5 on the BJB is the power point in the car. So if something's connected to the power point... well, unplug it.

It's probably not a chafed wire issue, that'd likely just short the circuit and blow the fuse directly. If the car's been modded in the particular areas for whatever reason, it might be that removing said mod maybe would resolve the problem...

I think that's it? I dunno. Electrics are weird, y'know. For what all that's worth. Hope it helps in some way.

Bert

I see Houtex already replied, but just confirming -- I believe something like 50-100 mA is "normal" when everything is "off"

I think you might need professional help on this one. I chased my tail for quite a while on a similar issue and finally gave up and paid a shop to do a diagnostic. It turned out my draw was normal and my problem was my battery; I understand your situation is different but my point is that it might be worth the money to pay someone to figure this one out.

jim010

Yes, it does help. Thank you Houtex.

I had my car sit for 2 days with fuse 5 pulled to see if that was the cure. Battery was below charge, so there is more going on. Back to the fuse box and pulling fuses. I will get my battery checked first, though as Bert suggests. Thinking my battery now may be the issue.

David Young

I went through something like you are going through with my old 91 F150. My battery would be to low to start it after sitting for 3 days. I bought a new battery and it still was to low to start after sitting for 3 days. Went to youtube and found a video on how to test fuses for parasitic draw. Tested every fuse (only had around 25) and everything tested good. Someone told me there is a diode inside the alternator that can go bad. The old alternator was charging the battery while the motor was running but I put a new rebuilt alternator in anyway, after all it was over 20 years old. It fixed my problem and that was around 3 years ago. Good luck on fixing your problem

jim010

I changed the battery today. I will let it sit for a day and see what happens.

jim010

Looks like a bad battery was the issue.

houtex

Glad to hear ya tracked it down, Jim, and thanks for the update!