The DTC was stored, no telling when it was generated. Disconnect the battery for a few minutes to clear any stored codes and see if any new codes are set after the engine has been started. 14.38 VDC alternator output at idle is pretty good, the regulator is typically set for 14.4 VDC max, but it could spike higher for a short duration. Where did you get the info that indicated DTC 26 was "high voltage" ?
02 Rodeo Sport 4X4 3.2L V6 73K miles