Description

With all emission related faults and when the Powertrain Control Module (PCM) commands Malfunction Indicator Lamp (MIL) (SERVICE ENGINE SOON) On, the PCM stores vehicle information into a memory called FREEZE FRAME. The freeze frame is a regulated requirement which allows for certain information to be stored. This information is data for a Diagnostic Trouble Code (DTC) that caused the MIL to illuminate for the first time. The Saturn portable diagnostic tool displays this information in the DTC MENU under the MALFUNCTION HISTORY directory as failure record "0." Malfunction history records the same data plus additional information and stores it in failure records numbered one through six. The malfunction history data records the same information as the emission freeze frame plus vital information specific to that failure. When the total recorded failures exceeds six, the oldest failure will be removed and the most recent installed as #1.
FREEZE FRAME 0 will store the following:
- DTC #
- Commanded Air/Fuel (A/F) ratio
- Calculated air flow
- Calculated load
- Engine Coolant Temperature (ECT)
- Barometric pressure
- Injector pulse width
- STFT
- LTFT
- Manifold Absolute Pressure (MAP)
- RPM
- Open/closed loop
- TP percent
- Vehicle Speed Sensor (VSS)
- Odometer reading at FIRST fault (odometer is reset to 0 when DTCs are cleared)
- Odometer reading at LAST fault (indicates the odometer miles the last time the DTC test failed).
- # Ignition cycles with 1 fail
- # Ignition cycles with 1 pass
- # Ignition cycles with no tests run

Malfunction history records one through six will store the above information as well as:
- IAT
- Engine run time
- Start-up ECT
- Gear and Torque Converter Clutch (TCC) status AIT
- If at idle
- Exhaust Gas Recirculation (EGR) On/Off
- A/C request status
- A/C relay command
- Coolant level state
- Brake On/Off
- Cooling fan command
- Evaporative Emission (EVAP) Canister purge On/Off

For most of the DTCs the malfunction history record will also store:
- 02S voltage
- Rear 02S voltage
- EGR valve pintle position
- Ignition volts

Some DTCs will replace these four parameters with specific data related to the DTC stored. Those parameters will aid in specific DTC diagnosis.
The MALFUNCTION HISTORY records for PCM EC/TC will record all of this information plus specific data related to the DTC. History record data will be erased from PCM memory during a DTC clear or after 40 warm-up cycles without any faults detected.