So once again little stupid issues have popped up on my 88 Subaru GL-10...I drove it for about 3 months with no issues..it has a brand new alternator and using a multimeter it is doing its job but no power was getting to the battery..I put a new wire in that goes from the back of the alternator tires into the main harness that goes into the car and also into the bottom of the fuse box under the good that then goes over to the positive on the battery..and yet the battery still went dead after driving for about 15 minutes...any suggestions would be very grateful! Thanks again!

If the alternator is good and the wiring is good, only thing left is a bad battery. 

I forgot to add that its a brand new battery as well only a week old..

Just guessing here but maybe the alternator current flows through one of the fusible links. And are you certain the car quits running because the battery is dead? Do the headlights still work or not? 

 

15 minutes of run time in the daytime without the headlights on and the battery goes dead? Tells me the battery started with a minimal charge. You should be able the run for hours with a fully charged battery and no alternator output. 

 

Just thought of something else that is a classic problem with the XT6 and just may apply here. The harmonic balancer separates and no longer turns the accessory belt. 

Edited June 29, 201411 yr by john in KY

Well it ran for 15 minutes after I replaced the wire...battery was only at about 12.5 volts when I fired it up but I have been dealing with this issue forabout a well and a half now...I think that the regulator in the alternator may be defective..

Make sure the battery warning light turns on when you turn the ignition key to ON or RUN. If that light doesn't work the alternator will not function. You should have near battery voltage on both of the wires on the back side of the alternator while the engine is running. If that is good then check the voltage at the output stud of the alternator. If that looks good then measure the voltage between that point and the positive battery post while charging. You should see less than a .3 volt difference if the wiring and fusible link are good. If you haven't checked the fusible links already they are in the small plastic box mounted on the coolant reservoir. Check for loose contact connections to the links. Some folks have found bad connections on the bottom side of the box also.