Installed Starter, Check
Test conditions: battery fully charged and ground connection correct.
Check starter cable: correct connection to starter and to battery positive terminal, maximum permissible voltage loss in cable should not be greater than 0.5 V when starting - measure voltage at starter terminal "50". If voltage loss is larger: check contact parts of ignition lock, selector lever switch, plug connector for adequate contact.
Check starter: connect Opel/Vauxhall tester - proceed as specified in User's Manual.