WARNING: This page is about a different car, the 2008 Suzuki Grand Vitara, 2007 Suzuki Grand Vitara, and 2006 Suzuki Grand Vitara. However, it is still accessible from the selected car via links, so may be relevant.
Check commutator and armature core. If there is continuity, armature is grounded and must be replaced.
Fig 1: Checking Continuity Between Commutator & Armature Core