Freeze frame data record the engine conditions (fuel system, calculated load, engine coolant temperature, fuel trim, engine speed, vehicle speed, etc.) when a malfunction is detected. When troubleshooting, it can help determine if the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was LEAN or RICH, and other data, from the time the malfunction occurred. HINT:

If it is impossible to replicate the problem even though a DTC is detected, confirm the freeze frame data. The ECM records engine conditions in the form of freeze frame data every 0.5 seconds. Using an intelligent tester, five separate sets of freeze frame data, including the data values at the time when the DTC was set, can be checked.

• 3 data sets before the DTC was set

These data sets can be used to simulate the conditions of the vehicle around the time of the occurrence of the malfunction. The data may assist in identifying of the cause of the malfunction, and in judging whether it was temporary or not.

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

Don't pay hundreds of dollars to find out what is wrong with your car. This book is dedicated to helping the do it yourself home and independent technician understand and use OBD-II technology to diagnose and repair their own vehicles.

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