Failure Code Determination

During any diagnostic procedure, "hard failure" codes MUST be distinguished from "intermittent failure" codes. Diagnostic charts CANNOT be used to analyze "intermittent failure" codes, except as noted under Diagnostic Procedure. To determine "hard failure" codes and "intermittent failure" codes, proceed as follows:

1. Turn ignition "ON" and enter diagnostics. Read and record all stored trouble codes. Exit diagnostics and clear trouble codes.
2. Apply parking brake and place manual transmission in neutral, or automatic transmission in "P" (park). Block drive wheels. Start engine. "CHECK ENGINE" light should go out. Run warm engine at specified curb idle for 5 minutes and note "CHECK ENGINE" light.
   NOTE: Grounding "TEST" terminal with engine running will force engine to operate in closed loop mode if engine is warm and oxygen sensor is hot. If "CHECK ENGINE " light does not glow while in closed loop, CCC system is operating properly.
3. If "CHECK ENGINE" light comes on, enter diagnostics. Read and record trouble codes. These are "hard failure" codes. Codes "13", "15", "24", "35", "44", "45" and "55" may require road test to reset "hard failure" after trouble codes were cleared.
4. If "CHECK ENGINE" light does not come on, all stored trouble codes were "intermittent failures", except as noted under Diagnostic Procedure.