Hello Mustang enthusiasts! I am looking for some advice o help my son. I started working on cars when I was a kid with my dad, so I am fairly handy with maintenance type work on my cars, but I don't know much about electrical.

My son has a 2015 Mustang convertible that he has put a lot of time and money in to customizing. He recently went out after a big rain to find about 2 inches of water in the drivers side floorboard. I took a look and told him his drain holes must be clogged, and both rear quarter panels were full of water. He moved the power seats all the way back, and put the top down and sucked out the water with the wet dry vac. All fine.

Then he tried to start the car to move it so we could jack it up - and it tried to turn over, and then died. 100% loss of all electrical. Completely dark. Now we don't even get a click when we turn the key.

We have had tons of rain since then and had to tarp it. On the one sunny day we had, I checked out the main fuse box and didn't see anything blown.
We also disconnected the battery for 30 minutes and then reconnected it.

Any ideas? Are there any in-line fuses in this thing? We are moving to Nashville in 13 days and I don't want to tow this car...but moving is expensive so I also don't want to drop 2k taking it to the dealer. Help please!

 

simple things first: check the battery (sounds like it is dead right now)

if you have a voltmeter, voltage across the terminals should be 12.2-12.4 volts after the car has been sitting for at least an hour or so

if it is less -- the battery needs to be charged first; and might need to be replaced if it does not hold a charge

next simple thing is to check the fuses; yes there are fuses and the locations should be shown in the owner's manual

 

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Hi Bert, thanks for the reply. The battery is good, and I did check all the fuses in both boxes already. What I was asking, is whether there might be a single "in-line" fuse on the 2015 Mustang, perhaps on the starter? I have sometimes seen cars that had single fuses that were not in the fuse boxes but rather on the electrical line itself to add protection for the starter and/or alternator. However - those were older vehicles and I am guessing the Mustang doesn't have one. I haven't found any reference to it online.

So, the battery is good and the fuses don't appear to be blown. What else might have shorted out when he tried to turn over the car?

Note - there was about 2 inches of water in the driver wheel well, but all the electrical was working FINE. He put the top down and the seat back and vacuumed out all the water and THEN he turned the ignition. The car tried to turn over but failed to start and all the electrical went dark.

I was wondering if it might be a blown starter solenoid? Would that kill all the power though? Thoughts?

 

Now when you say you checked the fuses are you talking about the fuse boxes (SJB) in the passenger footwell. And also no the starter will not prevent the car from having anything electrical light up as long as the battery is ok. The starter does just that start the vehicle. At least as far as I have ever known. Also for the drain plugs they are probably behind the cowl at the bottom of the windshield. At least that's where mine is but my car is older. It also sounds like there is a short somewhere, or a wire loose or a bad ground. If it was me I would go over every last wire testing them to see where it is. May just be a plug for something that got disconnected somehow or something. Sorry that you are having these troubles right before a move. Better now than in the middle of the move though. Glass half full kind of thinking.

 

I had the same issue with my 2005 GT Coupe. Some genius thought it would make sense to put rubber grommets in the drain holes under the cowl panel. This was directly under the cabin air filter on the passenger side and over time it filled with so much water it would soak into the filter and leak into the passenger compartment. There is a fuse panel next to the passenger side door that may have gotten wet and shorted out. Check under the cowl panel and see if you have the rubber plugs. If you do I'll bet you'll find a couple inches of standing water that you can drain out by pulling out the grommets and throwing said grommets in the trash where they belong.

 

That's the issue I had. Mine is a 07 and it filled up one day after a good rain and came into the passenger side the driver side was bad to. Also the doors have drains in them and they filled up also. Pulled them also. The water didnt get to my fuse box but had me worried for a little bit.

 

Hello everybody.

Anyone knows a fix for the original post, I have the same problem.