Code Output Format

CODE OUTPUT FORMAT
The EEC system communicates service information through the Diagnostic Trouble Code (DTC's).
These DTC's are three-digit numbers representing the results of On-Board Diagnosis.
The DTC's are transmitted on the Self-Test Output (STO) circuit found in the Data Link Connector (DLC).
They are in the form of timed pulses, and are read by the technician on a circuit-tester, SUPER STAR II, or Malfunction Indicator Light (MIL).




KEY ON ENGINE OFF AND CONTINUOUS MEMORY DTC FORMAT




ENGINE RUNNING DTC FORMAT

Fast DTC'S/Slow DTC's
Fast DTC's are issued prior to slow service DTC's. These DTC's contain the identical information as the slow DTC's, but are transmitted at 100 times the normal rate. These DTC's are interpreted by special equipment at the assembly line by the Body and Assembly Division as well as the SUPER STAR II tester.

Note: After Slow DTC's have been output, Self-Diagnosis should not be exited (remove jumper, unlatch button, etc.) until all the Slow DTC's have been output. Doing so will erase any Continuous Memory DTC's.

Continuous On-Board Diagnosis
The Continuous Memory DTC's are separated from the Key On Engine Off DTC's by a single separator pulse.

Note: During this mode of testing of testing the PCM continuously monitors inputs for opens and shorts. The Continuous Memory DTC's must be retrieved within 80 engine temperature warm up cycles. On the 81st Engine Temperature cycle, the DTC will be automatically erased. The Continuous Memory DTC's can also be erased by deactivating On-Board Diagnosis while the DTC's are being outputted.