We had to replace the alternator on my friends 1984 toyota truck because the pulley came apart. The new alternator will not charge. Took it back and they put it on the tester and it showed it was putting out 15volts. We replaced the voltage regulator and still have the same problem. We checked the fuses and connections and everything seems to be ok. Does anyone have any other ideas on what could be causing the problem? Thanks

 

Is the belt on and tight? Are you sure the wiring is hooked up right? Typically there needs to be a constant positive from the Alt to the VR to the Battery. Is the ground good, on both ends?

Also look for fusible links that may have toasted but you can't tell because they are inside the thick insulation. Use your VOM to probe continuity and voltage throughout the system.

My hunch is a bad fusible link or loose connection.