Freeze Frame Data
FREEZE FRAME DATAOBDII Freeze Frame Data
Freeze frame data allows access to emission related values from specific generic parameter identification (PID). These values are stored when an emission related diagnostic trouble code (DTC) is stored in continuous memory. This provides a snapshot of the conditions that were present when the DTC was stored. Once one set of freeze frame data is stored, this data remains in memory even if another emission related DTC is stored, with the exception of misfire or fuel system DTCs. Once freeze frame data for a misfire or fuel system DTC is stored it overwrites any previous data, and freeze frame data is no longer overwritten. When a DTC associated with the freeze frame data is erased or the DTCs are cleared, new freeze frame data can be stored again. In the event of multiple emission related DTCs in memory, always note the DTC for the freeze frame data.
FREEZE FRAME DATA TABLE
Some unique PIDs are stored in the keep alive memory (KAM) of the powertrain control module (PCM) to help in diagnosing the root cause of misfires. These PIDs are collectively called misfire freeze frame (MFF) data. These parameters are separate from the generic freeze frame data stored for every MIL code and are used for misfire diagnosis only. The MFF data could be more useful for misfire diagnosis than the generic freeze frame data. It is captured at the time of the highest misfire rate, not when the DTC is stored at the end of a 200 or 1,000 revolution block (generic freeze frame data for misfire can be stored minutes after the misfire actually occurred).
The MFF PIDs are supported on all vehicles, but may not be available on all scan tools because enhanced PID access may vary by scan tool manufacturer.
MISFIRE FREEZE FRAME PIDS
Manufacturer Specific Freeze Frame
The manufacturer specification freeze frame data is DTC snapshot data that allows a manufacturer to store vehicle condition information when a DTC sets. This is similar to the OBDII freeze frame functionality that already exists in the PCM. The manufacturer defines the snapshot data to provide the conditions at the time when a fault occurred. Each snapshot is about 40 - 50 PIDs with up to 5 snapshots available for up to 5 different DTCs. The PCM reports the most recent fault conditions for the DTC, and refreshes a maximum of once per operation cycle.
MANUFACTURER SPECIFIC FREEZE FRAME PIDS
