I have what others have described as an electrical issue associated with a malfunctioning Smart Junction Box (SJB). My garage diagnosed the issue over several days and associated with a SJB that needs replacing, however they did not pinpoint to the root cause which I believe, after reviewing other similar posts, is associated with water either coming in from the cabin air filter (due to the cowl becoming clogged with debris causing water to rise in the engine bay and flooding behind the glove box (SJB is apparently below the glove box on the passenger side) and/or the passenger side door. I have noticed the side door becoming clogged with debris at the bottom where the 2 rubber stoppers are and it then holds water for a period of time (I assume it rusts the inside).

The garage estimated a cost to replace the SJB at $1100 including replacement of the current battery which has likely become weakened from the extensive amount of self-starting I've needed to do to get the car going over the past several weeks. Note: this is not simply an issue of a weak battery. My battery was nearly new when this issue began and the garage confirmed as much. The SJB issues cause a draw much greater than the battery can power which keeps the car from starting many times, though not always.

From youtube I learned tools can be purchased to remove the windshield wipers and clean out the cowl though not sure if the rubber stoppers at the bottom should be completely removed or left in place and cleaned periodically (e.g., after large storms). I'm not sure if the stoppers serve a useful purpose. I also learned that the OEM grommets can be replaced with better ones and using a heat gun, can provide a better seal around the windshield.

I've heard that consumer complaints haven't lead to action/recall by Ford even though this is an apparent faulty design. Loved my mustang but not anymore. Moldy smell in car due to standing water is not a customer problem.

Very concerned with the random non start of the engine, but I have power to windows, lights, radio, dashboard lights. Not sure how to figure out where the exact location of the shortage may be considering the computer scan says somewhere between the ignition and battery.

Update from Oct 30, 2015: October 30, 2015 mileage now 109,100 and would not start again. Waited over 1 hour and no start. Had power to windows, lights, radio but would not turn over to start. Battery had full charge. Called tow truck and had car towed. Car started as it was being unloaded off of tow truck. It seems to be something over heating and once it cools down it starts up again. Suggestion of maybe a new key (maybe security chip bad); ignition switch is a possibility that needs to be changed. Another suggestion is to have ignition coil to be checked.

Have been told there is a shortage of some type between the ignition switch to battery (somewhere in between) but unable to pinpoint.

Update from Nov 4, 2015: November 3, 2015...while driving vehicle the check engine light came on I had no acceleration. I had to coast to a stop at which time the battery light came on then the oil light came on. Throughout this I had lights, radio, power windows worked. Pulled over to side of road and the car wouldn't start. Waited 20 minutes and car started. Same exact issue (as noted above) happened again as trying drive the car home.

Unable to get this problem fixed because no one can diagnose the issue. Once I can get an idea of why and how to fix it, I'll be more than happy to get the problem fixed. Until then, if anyone has any suggestions or if they are experiencing the same problem, please let me know!

This is an extremely DANGEROUS thing to have continuing to happen. Can result in an accident!