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Discussion Starter #1
I recently bought a 2007 V-6 convertible mustang repo. The battery has a dead short. Pulled each fuse trying to find the circuit with the short, still the test light you could see from the space station. Also removed the aftermarket radio also. Any help would be much appreciated!
 

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I had some electrical fun a while back. Try pulling the ground cable, then unplugging the 3 computer connections in the bay and plugging them back in. That fixed my issue.
 

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Before unplugging the computer connections...

Did you check for aftermarket radio stuff which might be in the trunk ?

Suggest removing, one at a time, all fuses both underhood and inside the car.
not clear if you've done that ?

Do you have copy of Owner's Guide which shows sort of, where all fuses go in each location ?

I can provide actual pics of underhood and interior fuse boxes with all fuses in their places...if you are not sure where they all go, after removing one or more.
There are many locations underhood with NO fuses in those locations..also a few places inside car fuse box with no fuses.
Note: Interior fuse box on this car is commonly called 'Smart Junction Box' or SJB.
Underhood fuse box called 'bussed electrical connector' also sometimes referred to as 'battery junction box.'

There should be examples of fuse box with fuses ...in the online service manual on this site.

http://iihs.net/fsm/?dir=40&viewfile=Fuse and Relay Information.pdf

Is it possible this is not just a repo, but could also be a flood car ?

And water leaks under dash are common on these cars (though less likely on a 2007 than 05 and 06). Those water leaks can cause electrical nightmares in some cars.
 

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Discussion Starter #5
I have removed all of the fuses one at a time, both under the hood and in the SJB in the car. I had a test light in between the negative post on the battery and the cable to check the load. Also, as other suggested I used a digital multi-meter in place of the test lights to see current changes.... Still no change. I did not see any amps or other equipment in the trunk. The underside of the dash shows no signs of water or flood damage. It is a convertible, could have been left out in the rain once or twenty times.. Have only had the car for a few days with no history at all.
 

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I am currently looking in a wiring diagrams manual from Ford ..to see if I have any more ideas.

It is not clear from you...Is this a running, working car ?
And if so, I'd suggest trying out all systems to see if everything works...lights, wipers, heater fan, power mirrors, everything you can think of.

The only other thing on the positive battery cable other than the starter is, somewhere, a grey wire to the alternator....and that has a fusible link (8 gauge black) within it. Oops that is only on V-6 cars,

O.K. so on the positive (red) battery cable, one heavy wire of it goes directly to starter motor. other red wire goes to underhood fuse box and directly to a 30amp fuse. Anything else other than these two, on positive battery battery cable would be aftermarket.

Everything on this car is fused, including various fuses, relays, diodes for the PCM...main underhood computer.
 

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Discussion Starter #7
The car works fine and is in amazing shape. Everything electrical works. It just has a load on the battery that keeps killing it. I bought this car for my daughter and really don't want to give her a car that's not reliable. I'm sure its going to be something stupid! The car came from Alabama, originally a rental in Orlando. Got the previous owner history from the carfax. I also disconnected the large wire from the Alt to see if that would make any difference. No such luck...
 

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I was mistaken about that alternator wire....I thought this a V-8.

Yes, only the V-6 has a wire from starter cable to B+ terminal of Alternator, which is a grey wire, with an 8 gauge black fusible link somewhere within itself.

Repeat, everything from factory on this car is fused (either underhood or inside car fuse boxes). So only explanation is that either there is an additional wire added, other than factory, to positive battery cable, OR you have not removed each and every fuse, relay, etc.

Note: there is a delay circuit, which allows somethings like radio, etc. to be used up to ten minutes after key removed. That delay circuit is deactivated as soon as a door is opened. And some cars have factory ACTIVE anti-theft system. If this car has that system, it would have sensors in corners of map light housing...above rearview mirror...and also would have hood open sensor of some type. And certainly the light on the dash, which flashes when car off, or locked, is part of a passive anti-theft system...which would create a parasitic battery draw.

I formerly had a V-6 coupe 2005. It was a great car.
Rentals usually have a fleet option...cigarette lighter (instead of 'power point') and ashtray, also bodyside molding. No other cars have these items.
 

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Discussion Starter #9
Mine does have a empty cig lighter socket in the center of the dash. Haven't seen a ashtray. No body side moulding but it has been repainted. Very badly I might add... Must have been the painters first day. I did find a GPS tracker unit under the dash. Removed the power wires and the box with the antenna puck. The only aftermarket stuff was the radio (which I thought was going to be the problem) but not. Took it out, now in the back seat.
 

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Note, in case you have to check these items:

Active anti theft system goes through Fuse #10 (5 amp) in SJB

Passive anti theft goes through Fuse #19 (5 amp) in SJB

There is also a ''power point" located in the console, and maybe a small socket there also for MP3 player connection I think, but not sure....that did not come on earlier cars like mine (05).

Power convertible top has fuses and relays underhood....fuses 51 and 13, and two relays there also.

Radio would have several fuses, depending on which radio (there were 3 from factory).
Radio fuses in SJB could be #6, #20
Radio fuses underhood could be #56, #14, #8, #5
Radio main amps two are above driver's kick panel, and if car has Shaker 1000 radio, two in trunk also.
 

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Discussion Starter #11
Have not thought about the delay circuit. My car does have the blinking security icon on the dash. Did not see any sensors up by the map lights. Looked under the hood today thinking it might have an engine bay light, but I did not see a hood open sensor. Had tried to make sure everything was off on the car while checking the fuses. Doors closed, radio turned off before turning off key, etc. I know others on this forum have talked about the parasitic draw on their cars. They use battery tenders if left over a few days, but mine seems to be more than just a little draw killing the battery over night. Battery says bought in Dec. But, still could have problems.
 

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All models have security icon (red) which flashes on dash.

Only Active models have hood open sensor. Sounds like yours does not have active...as it would also have sensors ...which look like tiny leds...facing interior of car...from edges of map light housing...they would be for motion detection.
A $300. option, not likely to be on a rental.

I would suggest going through removing all fuses again, to make sure you've done them all.
Easiest to see SJB clearly is to removed kick panel which covers it. First you have to remove door sill large plastic piece on passenger side of car....then kick panel can be removed by first pulling bottom of it out towards center (transmission tunnel area of interior), then grabbing it near door sill and pulling towards rear of car. All interior parts of this car very easy to deal with.
I will soon send pics of fuse boxes from my car with fuses in them.
Only difference I think, is that your car has additional stuff for power top in underhood fuse box, and maybe one fuse different as it has auto trans.

Interior fuses and relay could easily then all be removed at once, then put back...to then check for draw.

Underhood is a little more difficult as it has so many places with no fuses in those locations.
 

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I think only difference between your car and mine would be fuse and relays for power top, which I don't have.
They would be underhood.
Should be no difference between our cars in SJB (inside car)

Under hood you'd have a fuse 51 (10 amp), and two power top relays, lower right corner of that fuse box.

Additionally you'd have fuses underhood for REAR power windows...fuses 10 and 11 (30amps each)
 

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Discussion Starter #16
Thanks s197gt, I am headed to the shop this morning to work on my car. Thanks for the pics of the fuse boxes. Ill let you know how it goes... I now own two Mustangs and this website and forum have been a super resource for me! Thanks for all your help! Back soon...
 

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Discussion Starter #17
Unplugging/Re-Plugging the three connectors in the engine bay reduced the test light to a soft glow! Yea... I believe this will cure my problem. Thanks, again for all the help. Stored the pics of the fuse box for future reference. I believe the glow comes from the parasitic load from the radio, alarm, other minor continuous bs...
 
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