Component Tests and General Diagnostics
A scan tool can be connected to the Data Link Connector 
(DLC), this allows the scan tool to communicate with the Diesel 
Powertrain Control Module (PCM) Gasoline 
Vehicle Control Module (VCM) , the Inflatable Restraint Control Module, EVO/Passlock Module, Automatic Transfer Case Control Module, Transfer Case Control Module, or the Electronic Brake Control Module. System operations can then he monitored for diagnostic purposes.