PCM Power and Ground Circuit Troubleshooting (2.4 L Engine) (2017 2018 2019)

PCM Power and Ground Circuit Troubleshooting 

1. Engine starting check

   -1. Try to start the engine.

   Does the engine start and idle smoothly?

   YES 

   Go to the F-CAN circuit troubleshooting .

   NO 

   Go to step 2.

2. Fuse check 1

   -1. Check the following fuse.

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

   Is the fuse OK?

   YES 

   Go to step 6.

   NO 

   Go to step 3.

3. 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
   	Relay circuit board connector C (18P): disconnected
   Test point 1	Relay circuit board connector C (18P) (female terminals) No. 18:
   Test point 2	Body ground

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

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

   NO 

   Go to step 4.

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

   -1. Remove the injector relay .

   -2. Jump the SCS line with the HDS, and wait more than 1 minute.

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

   • PGM-FI main relay 2
   • PCM connector A (51P)

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

   Courtesy 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 5.

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

   Disconnect the following parts or connectors:

   • PGM-FI main relay 2
   • PCM connector A (51P)

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

   Test condition	Vehicle OFF (LOCK) mode
   	Relay circuit board connector C (18P): disconnected
   	PGM-FI main relay 2: disconnected
   	Injector relay: disconnected
   	PCM connector A (51P): disconnected
   Test point 1	Relay circuit board connector C (18P) (female terminals) No. 17:
   Test point 2	Body ground

   Courtesy 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.

6. Fuse check 2

   -1. Check the following fuse.

   Fuse	No. D8 (15 A)
   Location	Under-dash fuse/relay box

   Is the fuse OK?

   YES 

   Go to step 11.

   NO 

   Go to step 7.

7. 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 8.

   NO 

   Replace PGM-FI main relay 2. Also replace the No. D8 (15 A) fuse in the under-dash fuse/relay box.

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

   -1. Remove the blown No. D8 (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
   	PGM-FI main relay 2: disconnected
   Test point 1	PGM-FI main relay 2 4P socket (female terminals) No. 1:
   Test point 2	Body ground

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   Go to step 9.

   NO 

   Go to step 10.

9. Shorted wire check (IG1 FUEL PUMP line)

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

   -2. Disconnect the following connector.

   PCM connector A (51P)

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

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

   Test condition	Vehicle OFF (LOCK) mode
   	PGM-FI main relay 2: disconnected
   	Under-dash fuse/relay box connector C (27P): disconnected
   	PCM connector A (51P): disconnected
   Test point 1	PGM-FI main relay 2 4P socket (female terminals) No. 1:
   Test point 2	Body ground

   Test point 1	PCM connector A (51P) No. 4
   Test point 2	Body ground

   Courtesy 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, PCM (A4) and the No. D8 (15 A) fuse in the under-dash fuse/relay box. Also replace the No. D8 (15 A) fuse.

   NO 

   The IG1 FUEL PUMP wire is OK. Replace the No. D8 (15 A) fuse in the under-dash fuse/relay box. If the fuse blown again, replace the under-dash fuse/relay box .

10. 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
    	PGM-FI main relay 2: disconnected
    	PCM connector A (51P): disconnected
    	Fuel tank unit 4P connector: disconnected
    Test point 1	Fuel tank unit 4P connector (female terminals) No. 1:
    Test point 2	Body ground

    Courtesy 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. D8 (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. D8 (15 A) fuse in the under-dash fuse/relay box.

11. Open wire check (IG1 FUEL PUMP line) 1

    -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
    	PGM-FI main relay 2: disconnected
    Test point 1	PGM-FI main relay 2 4P socket (female terminals) No. 1:
    Test point 2	Body ground

    Courtesy of HONDA, U.S.A., INC.

    Is there battery voltage?

    YES 

    Go to step 12.

    NO 

    Repair an open in the IG1 FUEL PUMP wire between the No. D8 (15 A) fuse in the under-dash fuse/relay box and PGM-FI main relay 2.

12. Open wire check (IG1 FUEL PUMP line) 2

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

    -2. Disconnect the following connector.

    PCM connector A (51P)

    -3. Turn the vehicle to the ON mode.

    -4. Measure the voltage between test points 1 and 2.

    Test condition	Vehicle ON mode
    	PCM connector A (51P): disconnected
    	PGM-FI main relay 2: disconnected
    Test point 1	PCM connector A (51P) No. 4
    Test point 2	Body ground

    Is there battery voltage?

    YES 

    The IG1 FUEL PUMP wire is OK. Go to step 13.

    NO 

    Repair an open in the IG1 FUEL PUMP wire between the PCM (A4) and the No. D8 (15 A) fuse in the under-dash fuse/relay box.

13. 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 (51P): disconnected
    Test point 1	PCM connector A (51P) No. 3
    Test point 2	Body ground

    Is there battery voltage?

    YES 

    Go to step 16.

    NO 

    Go to step 14.

14. 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 (51P): disconnected
    	Relay circuit board connector C (18P): disconnected
    Test point 1	Relay circuit board connector C (18P) (female terminals) No. 18:
    Test point 2	Body ground

    Courtesy of HONDA, U.S.A., INC.

    Is there battery voltage?

    YES 

    Go to step 15.

    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.

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

    -1. Disconnect the following connector.

    Relay circuit board connector A (8P)

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

    Test condition	Vehicle OFF (LOCK) mode
    	PCM connector A (51P): disconnected
    	Relay circuit board connector A (8P): disconnected
    	Relay circuit board connector C (18P): disconnected
    Test point 1	Relay circuit board connector A (8P) (female terminals) No. 7:
    Test point 2	PCM connector A (51P) No. 3

    Courtesy 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 .

    NO 

    Repair an open in the FI MAIN RLY CL- wire between the PCM (A3) and the relay circuit board.

16. 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 (51P): disconnected
    	Relay circuit board connector C (18P): disconnected
    Test point 1	Relay circuit board connector C (18P) (female terminals) No. 17:
    Test point 2	PCM connector A (51P) No. 5

    Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    The FI MAIN RLY OUT wire is OK. Go to step 17.

    NO 

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

17. 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 18.

    NO 

    Replace the relay circuit board .

18. Open wire check (GND lines)

    -1. Disconnect the following connector.

    PCM connector B (51P)

    PCM connector C (51P)

    -2. Check for continuity between the following test points and body ground individually.

    Test condition	Vehicle OFF (LOCK) mode
    	PCM connector A (51P): disconnected
    	PCM connector E (80P): disconnected
    	Relay circuit board: removed

    Connector	Terminal
    PCM connector B (51P)	No. 11
    	No. 12
    PCM connector C (51P)	No. 1
    	No. 8

    Is there continuity?

    YES 

    The PGM (GND), GND1, GND2, and GND3 wires are OK. Check for any authorized service information related to the DTCs or symptoms you are troubleshooting, or substitute a known-good PCM .

    NO 

    Repair an open in the PGM, GND1, GND2, and/or GND3 wire between the PCM (B11, B12, C1, C8) and G101.