How do i Know if i need a new alternator.(Vauxhall corsa 1.3 CDTI )?

check the drive tension if to slack this will cause the burning smell,tighten the belt when happy with belt tension use a DMM (digital multi meter) set on DC scale at 20v start engine and run at 1500rpm the reading should be around the 14.5 v mark start turning on accessories alternator should still maintain approx the same voltage output
if your output is only 12v -12.5v replacement unit needed

wirecutterman
November 2011

just make sure you put the meter on high setting,

mm
November 2011

connect volt meter to the battery rev the car engine if the voltage increases then the alternator is ok,if not then it needs replaced

mm
November 2011