An Overview of the Self Diagnostic System

The ECU on all P7 and TCCS engines has a self diagnostic system which constantly monitors most of the electronic control system's input circuits. When the ECU detects a problem, it can turn on the check engine light to alert the driver that a fault exists in the system. At the same time, the ECU registers a diagnostic code in its keep alive memory so that the faulty circuit can be identified by a service technician at a later time.

if the circuit fault goes away, the check engine light will go off. However, the diagnostic code will remain in the ECU memory even after the ignition switch is turned off. For most engines, the contents of the diagnostic memory can be checked by shorting check connector terminals T (or TE1) and E1 together and counting the number of flashes on the check engine light.

After the problem has been repaired, the technician can clear the diagnostic system by removing the power from the ECU BATT feed.

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

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