"check charging system" intermittent computer display
This is an 05 Mustang GT convert, 66K miles. Only elec. mods were a "Battery Saver" low voltage interrupter, which I put on b/c I use a heat pad (don't have heated seats). I guess those items are a bit stuffy, and if I didn't use the car for 3-5days, it'd be cutting off ignition, even though I could start w. it removed at around 11.55v!
I also have a Pioneer AVIC-930 NAV, which I assumed was somehow putting some constant tricle flow out of the battery with the above scenario, so the Best Geek said the solution was simply to connect one wire direct to the battery. Don't ask me which wire, but the car would act like it was losing elec. power just taking turns thereafter, until I permanently removed the battery saver device. Since then, as it has gotten colder (Boston DUHH), I have been getting periodic "check charging system" on the tach systems status LED readout ribbon...usually within 15" of start up (no weird low elec energy turnover I can sense, tho). Running the stupid "check systems" button actually brings up "charging system ok"! Taking car to Autozone with their battery plug in showed 11.88v, and they told me to drive the S--T out of the car, they couldn't tell if it was the alternator.
I have a trickle charger, and used it after their advice a few times, which seemed to delay but not eliminate the stupid warning.
Sears did a Sears quality (aka cursory) battery test, said it was beyond their brainpower and sent me out. I've been calling FORD dealers who generally want $120 or more or diagnostics per hour. Some sales reps say to ignore it until it goes FUBAR. I am leaning towards that-it's an annoyance without any viable fault line, but I'm still blabbing here to see if anyone knows any ways around this stupid warning computer sign, or what is going on, as I've read there are a lot of folks that can't trace this but for 100's of hours or bucks. I don't think it's the radio. It might be aliens, or Daft Punk, but I'd like to be rid of it before I sell the car in a year or 3!