Operation-Pcm Ground
WARNING: This page is about a different car, the 2003 Dodge Intrepid, 2003 Chrysler Intrepid, 2003 Chrysler Concorde, and 2003 Chrysler 300M. However, it is still accessible from the selected car via links, so may be relevant.
Ground is provided through multiple pins of the PCM connector. There five different ground pins. There are engine power grounds and trans power grounds.
The power grounds are used to control the ground side of any relay, solenoid, ignition coil or injector.
The NGC case is shielded to prevent RFI and EMI. The PCM case is grounded and must be firmly attached to a good, clean body ground.
Internally all grounds are connected together. for EMI and RFI protection the case is also grounded separately from the ground pins.