PCM Power and Ground Circuit Troubleshooting

ElectronicCircuitSchematics-button

Engine starting check
-1. Start the engine.

Does the engine start and idle smoothly?

YES (without CAN gateway)

Go to the F-CAN circuit troubleshooting .

YES (with CAN gateway)

Go to step 2.

NO

Go to step 3.

CAN gateway system DTC check

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

-2. Turn the vehicle to the ON mode.

-3. Clear the DTC with the HDS.

-4. Turn the vehicle to the OFF (LOCK) mode.

-5. Turn the vehicle to the ON mode.

-6. Check for CAN gateway system DTCs with the HDS.

DTC Description	DTC

DTC (CAN GATEWAY)

Are any DTCs indicated?

YES

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

Intermittent failure, the system is OK at this time.

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

-2. Check the following fuse.

Fuse No. A21

Is the fuse OK?

YES

Go to step 7.

NO

Go to step 4.

Shorted wire check (+B MAIN RLY line)

-1. Remove the blown No. A21 fuse .

-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 fuse and the relay circuit board. If the wire is OK, replace the under-hood fuse/relay box . Also replace the No. A21 fuse.

Go to step 5.

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 A (50P)
CMP sensor 3P connector
CKP sensor 3P connector
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 fuse .

Parts are OK. Go to step 6.

Shorted wire check (IGP line):

Disconnect the following parts or connectors:

PGM-FI main relay 2
PCM connector A (50P)
CMP sensor 3P connector
CKP sensor 3P connector
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 A (50P): disconnected
	CMP sensor 3P connector: disconnected

	CKP sensor 3P connector: 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 fuse .

The IGP wire is OK. Replace the relay circuit board . Also replace the No. A21 fuse.

Fuse check 2
-1. Check the following fuse.

Fuse No. C6

Is the fuse OK?

YES

Go to step 12.

NO

Go to step 8.
Relay check
-1. Remove the blown No. C6 fuse .

-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 9.

NO

Replace PGM-FI main relay 2. Also replace the No. C6 fuse.

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 10.

Go to step 11.

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 (50P)

-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 (50P): disconnected
Test point 1	PCM connector A (50P) No. 6 - Refer to: PCM Connector for Inputs and Outputs or PCM Connector for Inputs and Outputs (2022 2023)
Test point 2	Body ground

Is there continuity?

YES

Repair a short in the IG1 FUEL PUMP wire between the PCM (A6) and the No. C6 fuse .

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 fuse.

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 fuse .

The +B FUEL PUMP wire is OK. Check the fuel pump, and replace it if needed. Also replace the No. C6 fuse.

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 (50P)

-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 (50P): disconnected
Test point 1	PCM connector A (50P) No. 6 - Refer to: PCM Connector for Inputs and Outputs or PCM Connector for Inputs and Outputs (2022 2023)
Test point 2	Body ground

Is there battery voltage?

YES

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

Repair an open in the IG1 FUEL PUMP wire between the PCM (A6) and the No. C6 fuse .

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 (50P): disconnected
Test point 1	PCM connector A (50P) No. 22 - Refer to: PCM Connector for Inputs and Outputs or PCM Connector for Inputs and Outputs (2022 2023)
Test point 2	Body ground

Is there battery voltage?

YES

Go to step 16.

Go to step 14.

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 (50P): 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 15.

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

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 (50P): 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 (50P) No. 22 - Refer to: PCM Connector for Inputs and Outputs or PCM Connector for Inputs and Outputs (2022 2023)

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 .

Repair an open in the M RLY wire between the PCM (A22) and the relay circuit board.

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 (50P): 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 17.

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

Open wire check (IGP line)

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

Test condition	Vehicle OFF (LOCK) mode
	PCM connector A (50P): disconnected
	Relay circuit board connector B (16P): disconnected
Test point 1	Relay circuit board connector B (16P) No. 8
Test point 2	PCM connector A (50P) No. 4 - Refer to: PCM Connector for Inputs and Outputs or PCM Connector for Inputs and Outputs (2022 2023)

Is there continuity?

YES

The IGP wire is OK. Go to step 18.

Repair an open in the IGP wire between the PCM (A4) and the relay circuit board.

Relay circuit board check
-1. Remove and test the relay circuit board .

Is the relay circuit board OK?

YES

Go to step 19.

NO

Replace the relay circuit board .

Open wire check (GND1, GND2 LG, GND3, GND4, GND5, PGM lines)

-1. Disconnect the following connector.

PCM connector E (80P)

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

Test condition	Vehicle OFF(LOCK) mode
	PCM connector A (50P): disconnected
	Relay circuit board connector B (16P): disconnected
	PCM connector E (80P): disconnected

Connector	Terminal
PCM connector E (80P) - Refer to: PCM Connector for Inputs and Outputs or PCM Connector for Inputs and Outputs (2022 2023)	No. 8, 15, 22, 25, 26, 27

Is there continuity?

YES

The GND1, GND2 LG, GND3, GND4, GND5, 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 .

Repair an open in the GND1, GND2 LG, GND3, GND4, GND5, and/or PGM wire between the PCM (E8, E15, E22, E25, E26, E27) and G101.