On Board Diagnostics II PCED

1999 PCED On Board Diagnostics II

SECTION 3: Symptom Charts

QT: Step 1: PCM Quick Test

QT1 PERFORM PCM QUICK TEST

Note: If the vehicle was brought in with an emission compliance failure symptom, GO directly to Section 5, Pinpoint Test Stem EM1 .

Complete preliminary checks looking for obvious concerns that may relate to the symptom. Check items such as those listed:

Related electrical connectors or fuses
Vacuum lines (leaks, routing)
Air intake system (leaks, restrictions)
Fuel quality (octane, contamination, winter/summer blend)
Cooling system (engine operating at proper temperature)

Access any related OASIS or TSB information (if available).
Complete PCM Quick Test to access any DTCs. Note any Key On Engine Off, Key On Engine Running (if engine runs) and Continuous Memory (MIL and non-MIL) DTCs.

Note: If unable to access DTCs, or any scan tool communication concern exists, go to Section 5, Pinpoint Test Step QA1 . For additional information on retrieving MIL and non-MIL DTCs, refer to Section 2 , Diagnostic Methods (Continuous Memory Self-Test).

Were any DTCs present?

Yes	No
If engine runs rough at idle and Key On Engine Running or Continuous Memory DTC(s) are present: GO to QT2 to check injector fault PIDS. All Others: GO to Section 4 (Powertrain DTC Charts) for direction to service DTC(s) after noting the following: Service DTCs in the following order (for each mode, begin diagnosis with the first DTC output). Any KOEO DTC(s) Any KOER DTC(s) Any Continuous Memory DTC(s) (retrieve any available Freeze Frame Data)(disregard any identical/related Continuous DTC(s) of DTC(s) already serviced).	GO to Step 2: NO DTC(s) PRESENT SYMPTOM CHART INDEX for direction to proper STEP 3 Chart. Note: If symptom is not listed, REFER to applicable Workshop Manual or GO to Section 5, Pinpoint Test Step Z1 (for intermittent PCM system diagnostics).

Yes

If engine runs rough at idle and Key On Engine Running or Continuous Memory DTC(s) are present:

GO to QT2 to check injector fault PIDS.

All Others:

GO to Section 4 (Powertrain DTC Charts) for direction to service DTC(s) after noting the following:

Service DTCs in the following order (for each mode, begin diagnosis with the first DTC output).

Any KOEO DTC(s)
Any KOER DTC(s)
Any Continuous Memory DTC(s) (retrieve any available Freeze Frame Data)(disregard any identical/related Continuous DTC(s) of DTC(s) already serviced).

GO to Step 2: NO DTC(s) PRESENT SYMPTOM CHART INDEX for direction to proper STEP 3 Chart.

Note: If symptom is not listed, REFER to applicable Workshop Manual or GO to Section 5, Pinpoint Test Step Z1 (for intermittent PCM system diagnostics).

QT2 ENGINE RUNS ROUGH AT IDLE WITH KEY ON ENGINE RUNNING OR CONTINUOUS MEMORY DTC(s): CHECK INJECTOR FAULT (INJxF) PID(s)

Note: An injector circuit fault could result in unrelated DTC(s) being received from the PCM.

Key on, engine off.
Access the INJxF PIDs (the "x" indicates the injector number). There will be one INJxF PID for each engine cylinder.

Do any of the INJxF PIDs indicate "Yes"?

Yes	No
An injector circuit fault exists. KEY OFF. Disregard DTC(s). For Natural Gas applications: GO to HA60 . All Others: GO to H56 .	No fault detected by injector fault PIDs. KEY OFF. RETURN to Step QT1 and follow the YES Action To Take for all others.