Genuine Autoelectro Premium Alternator 130A - AEK3201. We apologise in advance for any inconvenience caused. IG / S / L / M. S = Battery Sense / L = Warning Light / M = Monitor. A common cause for premature alternator clutch pulley failures can be due to a tensioning issue. Often the pulley is blamed but the main reason for the failure is due to excessive tension being applied to the pulley. Before replacing the alternator it is highly recommended that you inspect the original old unit alternator pulley for any defects. Check that the internal fan is turning when the pulley is rotated. Check the function of the clutch pulley mechanism. If the pulley is not functioning as it should then you have a pulley failure, this indicates that a vehicle fault needs investigating before the fitment of the replacement alternator as failure to do so may cause premature failure of the pulley on the replacement unit.