On-Board Diagnostic System

DESCRIPTION
When trouble occurs in the main input or output devices, check for the cause by using the SST. Failure of input and output devices is indicated and retrieved from the Engine Control Module (ECM) as diagnostic trouble codes.
For input devices, the ECM continuously checks for malfunction. For output devices, it checks for malfunctions only in a three-second period after the ignition switch is turned to ON, or the TEN terminal of the data link connector is grounded.