DTC Troubleshooting: P0657
DTC P0657: PCM Power Supply Circuit Malfunction
NOTE: Before you troubleshoot, review the general troubleshooting information.

DTC Description
Confirmed DTC
Pending DTC
P0657 PCM Power Supply Circuit Malfunction
    

1.
Problem verification:

Problem verification
?1.
Turn the vehicle to the ON mode.

?2.
Clear the DTC with the HDS.


?3.
Try to start the engine.

?4.
Check for Pending or Confirmed DTCs with the HDS.
DTC Description
Confirmed DTC
Pending DTC
P0657 PCM Power Supply Circuit Malfunction
    

Is DTC P0657 indicated?

     
YES
     
     
     
The failure is duplicated. Go to step 2.
     
NO
     
     
     
Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the relay circuit board (PGM-FI main relay 1 circuit) and the PCM. If the on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the on-board snapshot.?
2.
Relay circuit board check:

Relay circuit board check
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Remove and test the relay circuit board.

Is the relay circuit board OK?

     
YES
     
     
     
Go to step 3.
     
NO
     
     
     
3.
Fuse check:

Fuse check
?1.
Check the following fuse.
Fuse
No. A7 (15 A)
Location
Under-hood fuse/relay box

Is the fuse OK?

     
YES
     
     
     
Go to step 7.
     
NO
     
     
     
Go to step 4.
4.
Determine possible failure area (+B IGP line, others):

Determine possible failure area (+B IGP line, others)
?1.
Remove the blown No. A7 (15 A) fuse from the under-hood fuse/relay box.

?2.
Check for continuity the between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
 
Relay circuit board: removed
Test point 1
Relay circuit board connector C (18P) No. 18
Test point 2
Body ground


Is there continuity?

     
YES
     
     
     
Repair short in the +B IGP wire between the No. A7 (15 A) fuse in the under-hood fuse/relay box and the relay circuit board. Also replace the No. A7 (15 A) fuse.?
     
NO
     
     
     
Go to step 5.
5.
Parts internal circuit check:

Parts internal circuit check
?1.
Jump the SCS line with the HDS, and wait more than 1 minute.


?2.
Check for continuity between test points 1 and 2 while disconnecting these parts or connectors, one at a time:
PCM connector A (50P)
PGM-FI main relay 2
Each injector 2P connector

Test condition
Vehicle OFF (LOCK) mode
 
Relay circuit board: removed
Test point 1
Relay circuit board connector C (18P) No. 17
Test point 2
Body ground


Is continuity goes away with the part(s) removed?

     
YES
     
     
     
Replace the part that continuity goes away when it was disconnected. If the part is PCM, substitute a known-good PCM, then recheck. If DTC P0657 goes away and the PCM was substituted, replace the original PCM. Also replace the No. A7 (15 A) fuse.?
     
NO
     
     
     
Go to step 6.
6.
Shorted wire check (FI MAIN RLY OUT line):

Shorted wire check (FI MAIN RLY OUT line)
?1.
Disconnect the following parts and connectors.
PCM connector A (50P)
PGM-FI main relay 2
Each injector 2P connector

?2.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
 
Relay circuit board: removed
 
PCM connector A (50P): disconnected
 
PGM-FI main relay 2: disconnected
 
Each injector 2P connector: disconnected
Test point 1
Relay circuit board connector C (18P) No. 17
Test point 2
Body ground


Is there continuity?

     
YES
     
     
     
Repair short in the FI MAIN RLY OUT line between the PCM (A8), the relay circuit board, PGM-FI main relay 2, and the injectors. Also replace the No. A7 (15 A) fuse in the under-hood fuse/relay box.?
     
NO
     
     
     
Replace the relay circuit board. Also replace the No. A7 (15 A) fuse in the under-hood fuse/relay box.?
7.
Open wire check (+B IGP line):

Open wire check (+B IGP line)
?1.
Measure the voltage between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
 
Relay circuit board: removed
Test point 1
Relay circuit board connector C (18P) No. 18
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
The +B IGP wire is OK. Go to step 8.
     
NO
     
     
     
Repair an open in the +B IGP wire between the No. A7 (15 A) fuse in the under-hood fuse/relay box and the relay circuit board.?
8.
Open wire check (FI MAIN RLY CL- line):

Open wire check (FI MAIN RLY CL- line)
?1.
Jump the SCS line with the HDS, and wait more than 1 minute.


?2.
Disconnect the following connector.
PCM connector A (50P)

?3.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
 
Relay circuit board: removed
 
PCM connector A (50P): disconnected
Test point 1
Relay circuit board connector C (18P) No. 5
Test point 2
PCM connector A (50P) No. 5


Is there continuity?

     
YES
     
     
     
The FI MAIN RLY CL- wire is OK. Go to step 9.
     
NO
     
     
     
Repair an open in the FI MAIN RLY CL- wire between the PCM (A5) and the relay circuit board.?
9.
Open wire check (FI MAIN RLY OUT line):

Open wire check (FI MAIN RLY OUT line)
?1.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
 
Relay circuit board: removed
 
PCM connector A (50P): disconnected
Test point 1
Relay circuit board connector C (18P) No. 17
Test point 2
PCM connector A (50P) No. 8


Is there continuity?

     
YES
     
     
     
The FI MAIN RLY OUT wire is OK. Check for any authorized service information related to the DTCs or symptoms you are troubleshooting, or substitute a known-good PCM, then recheck. If DTC P0657 goes away and the PCM was substituted, replace the original PCM.?
     
NO
     
     
     
Repair an open in the FI MAIN RLY OUT wire between the PCM (A8) and the relay circuit board.?