DTC Advanced Diagnostics: P0657
DTC P0657:Powertrain Control Module (PCM) Power Supply Circuit Malfunction

General Description
Without Keyless Access System:

With Keyless Access System:

Main CPU and driver ICs are built into the powertrain control module (PCM). The main CPU receives drive commands and driver IC drives each corresponding devices. Power for the main CPU is provided from +B BACKUP FI-ECU line via CPU power supply, and power for the driver ICs are provided from FI MAIN RLY OUT line via PGM-FI main relay 1 circuit. If the FI MAIN RLY OUT voltage is a specified voltage for a specified time, the PCM detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type
Execution
Continuous
Sequence
None
Duration
5.0 seconds or more
DTC Type
One drive cycle, MIL on

Enable Conditions
Condition
Minimum
Maximum
12 volt battery voltage [BATTERY]
10.0 V
–
Vehicle
ON mode
[ ]: HDS Parameter

Malfunction Threshold
FI MAIN RLY OUT voltage is 6.0 V or less for at least 5.0 seconds.

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.
PGM-FI main relay 1 circuit failure
Fuse blown
PGM-FI main relay 1 circuit FI MAIN RLY OUT line open
PGM-FI main relay 1 circuit FI MAIN RLY CL- line open
PCM internal circuit failure

Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected, the MIL comes on and a Pending DTC, a Confirmed DTC, and the freeze data are stored in the PCM memory.

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 12 volt battery.