Advanced Diagnostics

Advanced Diagnostics - DTC P0685: Engine Control Module (ECM) Power Control Circuit/Internal Circuit Malfunction (Engine Type: K24Z7)

General Description






After the ignition switch is turned to LOCK (0), the engine control module (ECM) does not shut down immediately. After finishing a predetermined process according to the request of each device and system, the power supply is automatically disconnected (self shut-down function). The ECM power is disconnected by controlling PGM-FI main relay 1. During a normal ECM shut down, the shut down process is executed by the CPU, PGM-FI main relay 1 is turned off, and the voltage to the ECM is turned off to shut down the ECM. When the voltage to the ECM is turned off and the ECM shuts down without the normal shut down procedure, the ECM detects a malfunction in the PGM-FI main relay 1 control circuit and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status






Enable Conditions






Malfunction Threshold
The ECM is shut down within 1 second without the normal shut down procedure.

Possible Cause

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

- ECM internal circuit failure
- PGM-FI main relay 1 stuck open

Diagnosis Details

Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the ECM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC and the freeze data are stored.

Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the battery.