Q: 2007 ford explorer changed alternator battery still dying

A number of things things may affect the alternator not pushing current to the battery. The main feed wire to the battery is protected by a series "fusible links" in the line from the alternator through the junction box, to the battery. If that link opens, it should be visibly discolored or burnt-looking. Beyond this, there are two more fusible links, in series with each other, which connect to the junction of the first at the battery junction box, behind the battery. A short-circuited alternator can burn out any or all of these fuse links. They consist of a short length of wire several inches long, coated with special insulation. These are not "pull and replace" type fuses as you may be used to seeing. These are permanently wired-in. If blown, they must be cut out with a new link soldered in.

Open the cover of the fuse box; at the left end (front of vehicle) there is a nut holding two terminals which have the fuse links leaving the terminals downwards, and away. One is a thick red wire leading directly to the + battery terminal. The main link should be built into this. There should be a fuse in the vehicle fuse block on the driver’s side, fuse 21, 5 Amperes, which feeds the voltage regulator. This also activates the warning lamp. If that fuse is blown, the alternator will not charge, so you will want to check this first. If this fuse is blown, and it blows upon replacement, somewhere a short circuit exists. I would suggest having a professional from YourMechanic come to your location to diagnose and inspect your charging system.

Your charging system is controlled by the engine computer and if computer is not able to control the alternator the vehicle charging system will not operate. You may need to use an alternator from a dealer or authorized dealer part remanufacturer. Some aftermarket alternators are known to not work in these vehicles. Have the computer scanned for codes to see if it has codes stored that may need serviced first and then test computer ability to control alternator using the WDS scanner or equal. You may have a computer failure to control the alternator.