Freeze Frame Data

FREEZE FRAME DATA
The Engine Control Module (ECM) has a memory function which stores the driving condition at the moment the ECM detects a malfunction. This includes fuel system status, calculated load value, engine coolant temperature, short fuel trim, long fuel trim, engine speed, vehicle speed.
Stored data is called Freeze Frame Data.

The data is useful for tracking down conditions at the time of the malfunction. Such conditions include whether vehicle was running or stopped, engine warm up, air-fuel ratio, etc.
This data can be utilized to duplicate the malfunction and to diagnose the trouble.

The data will be erased along with the diagnostic trouble code by the above-mentioned method. The data can be stored only for the 1st trip. It can not be renewed even at the 2nd trip. The freeze frame data can be stored for only one item. Therefore, the ECM has the following priorities to update the data.




For example, an Exhaust Gas Recirculation (EGR) malfunction (Priority: 2) was detected and the freeze frame data was stored at the 1st trip. After that, misfire (Priority: 1) is detected in another trip, and freeze frame data is updated from the EGR malfunction for the misfire.