Corral Elite Member
Join Date: Nov 2000
Location: Chesterfield, MO
As one electrically-challenged Mustang owner to another: I feel your pain. I am no electrical wizard either but there are some troubleshooting things that you can do.
Even if a battery is new, it could have been sitting on a shelf for a year. Also, a new alternator may test fine on the assembly line but one component may randomly fail when it is put into service.
* Check the connectors to the alternator. Maybe one of the pins is not seating properly or a wire is broken.
* Check the connections to the battery. Corrosion is often a problem in the ground wire: it looks fine at the terminal connector but there is all sorts of green corroded wire hiding further down in the cable.
* Check the grounds on the motor. If you have a loose connection then this will cause all sorts of issues. When you stab the throttle the motor rotates a little and this can improve a loose connection. Of course, the higher RPM helps the alternator to charge the battery, too. Note that the alternator needs a minimum voltage from the battery to stimulate recharging and the output of the alternator is not constant (it increases with RPM).
* Do you have an aftermarket stereo or alarm? If so, the wiring has to be checked because there might be a leak to ground. You did not mention why the battery was replaced but aftermarket electronics/wiring can be a cause of battery problems.
Get yourself a VOM (volt-ohm meter). You don't need to be an electrical genius to use it (speaking from personal experience). You can get a reliable VOM for $30 (all the way up to several hundred dollars). It will allow you to check voltage and resistance or continuity and you will need this info when tracing electrical connection problems.
That's about all I can offer. I feel pretty good when I get the batteries in the flashlight correctly so let's hope somebody who knows a little about electrical stuff chimes in.
2012 GT 6MT - RTR #59; performance white / charcoal interior
3.73's, AED tune, MGW Race Spec shifter, Airaid MFT, BMR rear LCAs & relo brackets, Panhard rod & brace, FRPP swaybars, MRT a/c H-pipe, LP OTAs, FR GT500 Touring axlebacks, FRPP diff cover, JLT PCV p/s catchcan