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PCM Power and Ground Circuit Troubleshooting (K20C2)

  1. Engine starting check

    -1. Try to start the engine.

    Does the engine start and idle smoothly?

    YES (without multipurpose camera unit)

    Go to the F-CAN circuit troubleshooting .

    YES (with multipurpose camera unit)

    Go to the troubleshooting for CAN gateway system DTC (s) .

    NO 

    Go to step 2.

  2. Fuse check 1

    -1. Turn the vehicle to the OFF (LOCK) mode.

    -2. Check the following fuse.

    Fuse No. A12 (10 A)
    Location Under-hood fuse/relay box

    Is the fuse OK?

    YES 

    Go to step 3.

    NO 

    Go to step 4.

  3. Determine possible failure area (+B BACKUP FI-ECU line, others)

    -1. Jump the SCS line with the HDS, and wait more than 1 minute.

    -2. Disconnect the following connector.

    PCM connector A (50P)

    -3. Measure the voltage between test points 1 and 2.

    Test condition Vehicle OFF (LOCK) mode
      PCM connector A (50P): disconnected
    Test point 1 PCM connector A (50P) No. 7
    Test point 2 Body ground

    Is there battery voltage?

    YES 

    Go to step 5.

    NO 

    Repair an open in the +B BACKUP FI-ECU wire between the PCM (A7) and the No. A12 (10 A) fuse in the under-hood fuse/relay box.

  4. Shorted wire check (+B BACKUP FI-ECU 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
      PCM connector A (50P): disconnected
    Test point 1 PCM connector A (50P) No. 7
    Test point 2 Body ground

    Is there continuity?

    YES 

    Repair a short in the +B BACKUP FI-ECU wire between the PCM (A7) and the No. A12 (10 A) fuse in the under-hood fuse/relay box.

    NO 

    Go to step 5.

  5. Fuse check 2

    -1. Check the following fuse.

    Fuse No. A7 (15 A)
    Location Under-hood fuse/relay box

    Is the fuse OK?

    YES 

    Go to step 9.

    NO 

    Go to step 6.

  6. Shorted wire check (+B IGP line)

    -1. Remove the blown No. A7 (15 A) fuse from the under-hood fuse/relay box.

    -2. Disconnect the following connector.

    Relay circuit board connector C (18P)

    -3. Check for continuity between test points 1 and 2.

    Test condition Vehicle OFF (LOCK) mode
      PCM connector A (50P): disconnected
      Relay circuit board connector C (18P): disconnected
    Test point 1 Relay circuit board connector C (18P) No. 18
    Test point 2 Body ground
    GHH407075Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    Repair a short in the +B IGP wire between the relay circuit board and the No. A7 (15 A) fuse. If the wire is OK, replace the under-hood fuse/relay box . Also replace the No. A7 (15 A) fuse.

    NO 

    Go to step 7.

  7. Part (s) internal circuit check (short in FI MAIN RLY OUT line):

    Disconnect each of the parts or connectors below, one at a time, then check for continuity between test points 1 and 2.

    • PCM connector A (50P)
    • PGM-FI main relay 2
    • Each injector 2P connector
    Test condition Vehicle OFF (LOCK) mode
    Relay circuit board connector C (18P): disconnected
    Test point 1 Relay circuit board connector C (18P) No. 17
    Test point 2 Body ground
    GHH407076Courtesy of HONDA, U.S.A., INC.

    Does continuity go away when one of the above components is disconnected?

    YES 

    Replace the part that made the short to body ground go away when it was disconnected. If the part is the PCM, check for any authorized service information related to the DTCs or symptoms you are troubleshooting, or substitute a known-good PCM , then recheck. If the symptom/indication goes away and the PCM was substituted, replace the original PCM . Also replace the No. A7 (15 A) fuse in the under-hood fuse/relay box.

    NO 

    Parts are OK. Go to step 8.

  8. Shorted wire check (FI MAIN RLY OUT line):

    Disconnect the following parts or 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 connector C (18P): disconnected
      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
    GHH407077Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    Repair a short in the FI MAIN RLY OUT wire between the relay circuit board and each part. Also replace the No. A7 (15 A) fuse in the under-hood fuse/relay box.

    NO 

    The FI MAIN RLY OUT wire is OK. Replace the relay circuit board . Also replace the No. A7 (15 A) fuse in the under-hood fuse/relay box.

  9. Fuse check 3

    -1. Check the following fuse.

    Fuse No. B8 (15 A)
    Location Under-dash fuse/relay box

    Is the fuse OK?

    YES 

    Go to step 14.

    NO 

    Go to step 10.

  10. Relay check

    -1. Remove PGM-FI main relay 2 .

    -2. Test PGM-FI main relay 2 .

    Is the relay OK?

    YES 

    PGM-FI main relay 2 is OK. Go to step 11.

    NO 

    Replace PGM-FI main relay 2. Also replace the No. B8 (15 A) fuse in the under-dash fuse/relay box.

  11. Determine possible failure area (IG1 FUEL PUMP line, others)

    -1. Remove the blown No. B8 (15 A) fuse from the under-dash fuse/relay box.

    -2. Check for continuity between test points 1 and 2.

    Test condition Vehicle OFF (LOCK) mode
      PCM connector A (50P): disconnected
      PGM-FI main relay 2: disconnected
    Test point 1 PGM-FI main relay 2 4P socket No. 1
    Test point 2 Body ground
    GHH407078Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    Go to step 12.

    NO 

    Go to step 13.

  12. Shorted wire check (IG1 FUEL PUMP line)

    -1. Disconnect the following connector.

    Under-dash fuse/relay box connector C (27P)

    -2. Check for continuity between test points 1 and 2.

    Test condition Vehicle OFF (LOCK) mode
      PCM connector A (50P): disconnected
      PGM-FI main relay 2: disconnected
      Under-dash fuse/relay box connector C (27P): disconnected
    Test point 1 PGM-FI main relay 2 4P socket No. 1
    Test point 2 Body ground
    GHH407079Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    Repair a short in the IG1 FUEL PUMP wire between PGM-FI main relay 2 and the under-dash fuse/relay box. Also replace the No. B8 (15 A) fuse in the under-dash fuse/relay box.

    NO 

    The IG1 FUEL PUMP wire is OK. Replace the No. B8 (15 A) fuse in the under-dash fuse/relay box. If the fuse blown again, replace the under-dash fuse/relay box .

  13. Shorted wire check (FUEL PUMP RLY OUT line)

    -1. Disconnect the following connector.

    Fuel tank unit 4P connector

    -2. Check for continuity between test points 1 and 2.

    Test condition Vehicle OFF (LOCK) mode
      PCM connector A (50P): disconnected
      PGM-FI main relay 2: disconnected
      Fuel tank unit 4P connector: disconnected
    Test point 1 Fuel tank unit 4P connector No. 1
    Test point 2 Body ground
    GHH407080Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    Repair a short in the FUEL PUMP RLY OUT wire between PGM-FI main relay 2 and the fuel tank unit. Also replace the No. B8 (15 A) fuse in the under-dash fuse/relay box.

    NO 

    The FUEL PUMP RLY OUT wire is OK. Check the fuel pump, and replace it if needed. Also replace the No. B8 (15 A) fuse in the under-dash fuse/relay box.

  14. Open wire check (IG1 FUEL PUMP line)

    -1. Remove PGM-FI main relay 2 .

    -2. Turn the vehicle to the ON mode.

    -3. Measure the voltage between test points 1 and 2.

    Test condition Vehicle ON mode
      PCM connector A (50P): disconnected
      PGM-FI main relay 2: disconnected
    Test point 1 PGM-FI main relay 2 4P socket No. 1
    Test point 2 Body ground
    GHH407081Courtesy of HONDA, U.S.A., INC.

    Is there battery voltage?

    YES 

    The IG1 FUEL PUMP wire is OK. Go to step 15.

    NO 

    Repair an open in the IG1 FUEL PUMP wire between the No. B8 (15 A) fuse in the under-dash fuse/relay box and PGM-FI main relay 2.

  15. Fuse check 4

    -1. Turn the vehicle to the OFF (LOCK) mode.

    -2. Check the following fuse.

    Fuse No. B11 (5 A)
    Location Under-dash fuse/relay box

    Is the fuse OK?

    YES 

    Go to step 17.

    NO 

    Go to step 16.

  16. Shorted wire check (IG1 (MONI)/IG1 MON line)

    -1. Disconnect the following connector.

    PCM connector E (80P)

    -2. Check for continuity between test points 1 and 2.

    Test condition Vehicle OFF (LOCK) mode
      PCM connector A (50P): disconnected
      PGM-FI main relay 2: disconnected
      PCM connector E (80P): disconnected
    Test point 1 PCM connector E (80P) No. 36
    Test point 2 Body ground

    Is there continuity?

    YES 

    Repair a short in the IG1 (MONI)/IG1 MON wire between the PCM (E36) and the No. B11 (5 A) fuse in the under-dash fuse/relay box. Also replace the No. B11 (5 A) fuse.

    NO 

    The IG1 (MONI)/IG1 MON wire is not shorted. Go to step 17.

  17. Open wire check (IG1 (MONI)/IG1 MON line)

    -1. Replace the No. B11 (5 A) fuse.

    -2. Turn the vehicle to the ON mode.

    -3. Measure the voltage between test points 1 and 2.

    Test condition Vehicle ON mode
      PCM connector A (50P): disconnected
      PGM-FI main relay 2: disconnected
      PCM connector E (80P): disconnected
    Test point 1 PCM connector E (80P) No. 36
    Test point 2 Body ground

    Is there battery voltage?

    YES 

    The IG1 (MONI)/IG1 MON wire is OK. Go to step 18.

    NO 

    Repair an open in the IG1 (MONI)/IG1 MON wire between the PCM (E36) and the No. B11 (5 A) fuse in the under-dash fuse/relay box.

  18. Determine possible failure area (PGM-FI main relay 1 control circuit, others)

    -1. Turn the vehicle to the OFF (LOCK) mode.

    -2. Measure the voltage between test points 1 and 2.

    Test condition Vehicle OFF (LOCK) mode
      PCM connector A (50P): disconnected
      PGM-FI main relay 2: disconnected
      PCM connector E (80P): disconnected
    Test point 1 PCM connector A (50P) No. 5
    Test point 2 Body ground

    Is there battery voltage?

    YES 

    Go to step 21.

    NO 

    Go to step 19.

  19. Open wire check (+B IGP line)

    -1. Disconnect the following connector.

    Relay circuit board connector C (18P)

    -2. Measure the voltage between test points 1 and 2.

    Test condition Vehicle OFF (LOCK) mode
      PCM connector A (50P): disconnected
      PGM-FI main relay 2: disconnected
      PCM connector E (80P): disconnected
      Relay circuit board connector C (18P): disconnected
    Test point 1 Relay circuit board connector C (18P) No. 18
    Test point 2 Body ground
    GHH407082Courtesy of HONDA, U.S.A., INC.

    Is there battery voltage?

    YES 

    Go to step 20.

    NO 

    Repair an open in the +B IGP wire between the relay circuit board and the No. A7 (15 A) fuse in the under-hood fuse/relay box.

  20. Open wire check (FI MAIN RLY CL- line)

    -1. Check for continuity between test points 1 and 2.

    Test condition Vehicle OFF (LOCK) mode
      PCM connector A (50P): disconnected
      PGM-FI main relay 2: disconnected
      PCM connector E (80P): disconnected
      Relay circuit board connector C (18P): disconnected
    Test point 1 Relay circuit board connector C (18P) No. 5
    Test point 2 PCM connector A (50P) No. 5
    GHH407083Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    The FI MAIN RLY CL- wire is OK. Remove and test the relay circuit board . If the relay circuit board 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 the symptom/indication goes away and the PCM was substituted, replace the original PCM .

    NO 

    Repair an open in the FI MAIN RLY CL- wire between the PCM (A5) and the relay circuit board.

  21. Open wire check (FI MAIN RLY OUT line)

    -1. Disconnect the following connector.

    Relay circuit board connector C (18P)

    -2. Check for continuity between test points 1 and 2.

    Test condition Vehicle OFF (LOCK) mode
      PCM connector A (50P): disconnected
      PGM-FI main relay 2: disconnected
      PCM connector E (80P): disconnected
      Relay circuit board connector C (18P): disconnected
    Test point 1 Relay circuit board connector C (18P) No. 17
    Test point 2 PCM connector A (50P) No. 8
    GHH407084Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    The FI MAIN RLY OUT wire is OK. Go to step 22.

    NO 

    Repair an open in the FI MAIN RLY OUT wire between the PCM (A8) and the relay circuit board.

  22. Relay circuit board check

    -1. Remove and test the relay circuit board .

    Is the relay circuit board OK?

    YES 

    The relay circuit board is OK. Go to step 23.

    NO 

    Replace the relay circuit board .

  23. Open wire check (FI ECU GND line, PG line, PG (COIL) line, GND2 line)

    -1. Check for continuity between the following test points and body ground individually.

    Test condition Vehicle OFF (LOCK) mode
      PCM connector A (50P): disconnected
      PGM-FI main relay 2: disconnected
      PCM connector E (80P): disconnected
      Relay circuit board: removed
    Connector Terminal
    PCM connector A (50P) No. 13
    PCM connector E (80P) No. 22, 23, and 24

    Is there continuity?

    YES 

    The FI ECU GND wire, the PG wire, the PG (COIL) wire, and the GND2 wire are 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 the symptom/indication goes away and the PCM was substituted, replace the original PCM .

    NO 

    Repair an open in the FI ECU GND wire, the PG wire, the PG (COIL) wire, and/or the GND2 wire between the PCM (A13, E22, E23, and/or E24) and G101.

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