PCM Power and Ground Circuit Troubleshooting (2017 2018 2019)

NOTE:  Information marked with an asterisk (*) applies to the AC power outlet equipped model.

1. Engine starting check

   -1. 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. Check the following fuse.

   Fuse	With AC power outlet: No. A16 (15 A)
   	Without AC power outlet: No. A21 (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 MAIN RLY line)

   -1. Remove the blown No. A21 (15 A), (No. A16 (15 A)) * fuse from the under-hood fuse/relay box.

   -2. Disconnect the following connector.

   Relay circuit board connector B (16P)

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

   Test condition	Vehicle OFF (LOCK) mode
   	Relay circuit board connector B (16P): disconnected
   Test point 1	Relay circuit board connector B (16P) No. 4
   Test point 2	Body ground

   Is there continuity?

   YES 

   Repair a short in the +B MAIN RLY wire between the No. A21 (15 A), (No. A16 (15 A)) * fuse and the relay circuit board. If the wire is OK, replace the under-hood fuse/relay box . Also replace the No. A21 (15 A), (No. A16 (15 A)) * fuse.

   NO 

   Go to step 4.

4. Part(s) internal circuit check (short in IGP line)

   -1. 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 B (51P)
   • CMP sensor 3P connector
   • CKP sensor 3P connector
   • Injector relay (direct fuel-injected engine)
   • Radiator fan relay

   Test condition	Vehicle OFF (LOCK) mode
   	Relay circuit board connector B (16P): disconnected
   Test point 1	Relay circuit board connector B (16P) No. 8, No. 9, and No. 10
   Test point 2	Body ground

   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, 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. A21 (15 A), (No. A16 (15 A))* fuse in the under-hood fuse/relay box.

   NO 

   Parts are OK. Go to step 5.

5. Shorted wire check (IGP line):

   Disconnect the following parts or connectors:

   • PGM-FI main relay 2
   • PCM connector B (51P)
   • CMP sensor 3P connector
   • CKP sensor 3P connector
   • Injector relay (direct fuel-injected engine)
   • Radiator fan relay

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

   Test condition	Vehicle OFF (LOCK) mode
   	Relay circuit board connector B (16P): disconnected
   	PGM-FI main relay 2: disconnected
   	PCM connector B (51P): disconnected
   	CMP sensor 3P connector: disconnected
   	CKP sensor 3P connector: disconnected
   	Injector relay (direct fuel-injected engine): disconnected
   	Radiator fan relay : disconnected
   Test point 1	Relay circuit board connector B (16P) No. 8, No. 9, and No. 10
   Test point 2	Body ground

   Is there continuity?

   YES 

   Repair a short in the IGP wire between the relay circuit board and each part. Also replace the No. A21 (15 A), (No. A16 (15 A)) * fuse in the under-hood fuse/relay box.

   NO 

   The IGP wire is OK. Replace the relay circuit board . Also replace the No. A21 (15 A), (No. A16 (15 A)) * fuse in the under-hood fuse/relay box.

6. Fuse check 2

   -1. Check the following fuse.

   Fuse	No. C6 (20 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 the blown No. C6 (20 A) fuse from the under-dash fuse/relay box.

   -2. Remove PGM-FI main relay 2 .

   -3. 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. C6 (20 A) fuse.

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

   -1. 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. 2:
   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)

   -3. 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
   Test point 1	PCM connector A (51P) No. 18
   Test point 2	Body ground

   Is there continuity?

   YES 

   Repair a short in the IG1 FUEL PUMP wire between the PCM (A18) and the No. C6 (20 A) fuse in the under-dash fuse/relay box.

   NO 

   The IG1 FUEL PUMP wire is OK. Check for any authorized service information related to the DTCs or symptoms you are troubleshooting or substitute a known-good PCM . Also replace the No. C6 (20 A) fuse in the under-dash fuse/relay box.

10. Shorted wire check (+B FUEL PUMP 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
    	Fuel tank unit 4P connector: 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 

    Repair a short in the +B FUEL PUMP wire between PGM-FI main relay 2 and the fuel tank unit. Also replace the No. C6 (20 A) fuse in the under-dash fuse/relay box.

    NO 

    The +B FUEL PUMP wire is OK. Check the fuel pump, and replace it if needed. Also replace the No. C6 (20 A) fuse in the under-dash fuse/relay box.

11. Open 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)

    -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
    Test point 1	PCM connector A (51P) No. 18
    Test point 2	Body ground

    Is there battery voltage?

    YES 

    The IG1 FUEL PUMP wire is OK. Go to step 12.

    NO 

    Repair an open in the IG1 FUEL PUMP wire between the PCM (A18) and the No. C6 (20 A) fuse in the under-dash fuse/relay box.

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

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

    Test condition	Vehicle ON mode
    	PCM connector A (51P): disconnected
    Test point 1	PCM connector A (51P) No. 7
    Test point 2	Body ground

    Is there battery voltage?

    YES 

    Go to step  15.

    NO 

    Go to step 13.

13. Open wire check (+B MAIN RLY line)

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

    -2. Disconnect the following connector.

    Relay circuit board connector B (16P)

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

    Test condition	Vehicle OFF (LOCK) mode
    	PCM connector A (51P): disconnected
    	Relay circuit board connector B (16P): disconnected
    Test point 1	Relay circuit board connector B (16P) No. 4
    Test point 2	Body ground

    Is there battery voltage?

    YES 

    Go to step 14.

    NO 

    Repair an open in the +B MAIN RLY wire between the relay circuit board and the No. A21 (15 A), (No. A16 (15 A)) * fuse in the under-hood fuse/relay box. If the wire is OK, replace the under-hood fuse/relay box . Also replace the No. A21 (15 A), (No. A16 (15 A)) * fuse.

14. Open wire check (M RLY line)

    -1. Disconnect the following connector.

    Relay circuit board connector A (10P)

    -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 B (16P): disconnected
    	Relay circuit board connector A (10P): disconnected
    Test point 1	Relay circuit board connector A (10P) No. 9
    Test point 2	PCM connector A (51P) No. 7

    Is there continuity?

    YES 

    The FI M RLY 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 M RLY wire between the PCM (A7) and the relay circuit board.

15. Open wire check (+B MAIN RLY line)

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

    -2. Disconnect the following connector.

    Relay circuit board connector B (16P)

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

    Test condition	Vehicle OFF (LOCK) mode
    	PCM connector A (51P): disconnected
    	Relay circuit board connector B (16P): disconnected
    Test point 1	Relay circuit board connector B (16P) No. 4
    Test point 2	Body ground

    Is there battery voltage?

    YES 

    Go to step 16.

    NO 

    Repair an open in the +B MAIN RLY wire between the relay circuit board and the No. A21 (15 A), (No. A16 (15 A)) * fuse in the under-hood fuse/relay box. If the wire is OK, replace the under-hood fuse/relay box .

16. Open wire check (IGP line)

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

    -2. Disconnect the following connector.

    PCM connector B (51P)

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

    Test condition	Vehicle OFF (LOCK) mode
    	PCM connector A (51P): disconnected
    	Relay circuit board connector B (16P): disconnected
    	PCM connector B (51P): disconnected
    Test point 1	Relay circuit board connector B (16P) No. 8
    Test point 2	PCM connector B (51P) No. 10

    Is there continuity?

    YES 

    The IGP wire is OK. Go to step 17.

    NO 

    Repair an open in the IGP wire between the PCM (B10) 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 

    Go to step 18.

    NO 

    Replace the relay circuit board .

18. Open wire check (GND1, GND2 LG, GND3, PGM lines)

    -1. Disconnect the following connector.

    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
    	Relay circuit board connector B (16P): disconnected
    	PCM connector B (51P): disconnected
    	PCM connector C (51P): disconnected

    Connector	Terminal
    PCM connector B (51P)	No. 11
    	No. 20
    PCM connector C (51P)	No. 1
    	No. 20

    Is there continuity?

    YES 

    The GND1, GND2 LG, GND3, and PGM 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 GND1, GND2 LG, GND3, and/or PGM wire between the PCM (B11, B20, C1, C20) and G101.