PCM Power and Ground Circuit Troubleshooting

1.

Engine starting check:

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:

Fuse check

?1.

Check the following fuse.

Fuse	No. B7 (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):

Shorted wire check (+B IGP line)

?1.	Remove the blown No. B7 (15 A) fuse from the under-hood fuse/relay box.

?2.	Remove PGM-FI main relay 1 (A) from the under-hood fuse/relay box.

?3.

Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	PGM-FI main relay 1: disconnected
Test point 1	PGM-FI main relay 1 4P socket No. 1 and No. 3
Test point 2	Body ground

Is there continuity?


	YES

Repair a short in the +B IGP wire(s) between the No. B7 (15 A) fuse and PGM-FI main relay 1. If the wires are OK, replace the under-hood fuse/relay box. Also replace the No. B7 (15 A) fuse.?


	NO

Go to step 4.

4.

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

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

?1.	Jump the SCS line with the HDS.

?2.

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)
	CMP sensor 3P connector
	CKP sensor 3P connector
	Injector relay
	Electronic throttle control system (ETCS) control relay

Test condition	Vehicle OFF (LOCK) mode
Test circuit	FI MAIN RLY OUT
Test point 1	PGM-FI main relay 1 4P socket No. 2
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, update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away and the PCM was updated, troubleshooting is complete. If the symptom/indication goes away and the PCM was substituted, replace the original PCM. Also replace the No. B7 (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):

Shorted wire check (FI MAIN RLY OUT line)

?1.

Disconnect the following parts or connectors:

	PGM-FI main relay 2
	PCM connector A (51P)
	CMP sensor 3P connector
	CKP sensor 3P connector
	Injector relay
	Electronic throttle control system (ETCS) control relay

?2.

Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	PGM-FI main relay 1: disconnected
	PGM-FI main relay 2: disconnected
	PCM connector A (51P): disconnected
	CMP sensor 3P connector: disconnected
	CKP sensor 3P connector: disconnected
	Injector relay: disconnected
	Electronic throttle control system (ETCS) control relay: disconnected
Test circuit	FI MAIN RLY OUT
Test point 1	PGM-FI main relay 1 4P socket No. 2
Test point 2	Body ground

Is there continuity?


	YES

Repair a short in the FI MAIN RLY OUT wire between PGM-FI main relay 1 and each part. Also replace the No. B7 (15 A) fuse in the under-hood fuse/relay box.?


	NO

The FI MAIN RLY OUT wire is OK. Replace PGM-FI main relay 1. Also replace the No. B7 (15 A) fuse in the under-hood fuse/relay box.?

6.

Fuse check 2:

Fuse check 2

?1.

Check the following fuse.

Fuse	No. C32 (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:

Relay check

?1.	Remove the blown No. C32 (15 A) fuse from the under-dash fuse/relay box.

?2.	Remove PGM-FI main relay 2 (A) from the under-dash fuse/relay box.

?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. C32 (15 A) fuse.?

8.

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

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 No. 2
Test point 2	Body ground

Is there continuity?


	YES

Go to step 9.


	NO

Go to step 10.

9.

Shorted wire check (IG1 FUEL PUMP line):

Shorted wire check (IG1 FUEL PUMP line)

?1.	Jump the SCS line with the HDS.

?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. 4
Test point 2	Body ground

Is there continuity?


	YES

Repair a short in the IG1 FUEL PUMP wire between the No. C32 (15 A) fuse in the under-dash fuse/relay box and the PCM (A4).?


	NO

The IG1 FUEL PUMP wire is OK. Replace the No. C32 (15 A) fuse in the under-dash fuse/relay box, and update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away and the PCM was updated, troubleshooting is complete. If the symptom/indication goes away and the PCM was substituted, replace the original PCM.?

10.

Shorted wire check (FUEL PUMP RLY OUT line):

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
	Fuel tank unit 4P connector: disconnected
Test point 1	Fuel tank unit 4P connector No. 1
Test point 2	Body ground

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. C32 (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. C32 (15 A) fuse in the under-dash fuse/relay box.?

11.

Open wire check (IG1 FUEL PUMP line):

Open wire check (IG1 FUEL PUMP line)

?1.	Jump the SCS line with the HDS.

?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. 4
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 No. C32 (15 A) fuse in the under-dash fuse/relay box and the PCM (A4).?

12.

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

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 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 15.


	NO

Go to step 13.

13.

Open wire check (+B IGP line):

Open wire check (+B IGP line)

?1.	Remove PGM-FI main relay 1 (A) from the under-hood fuse/relay box.

?2.

Measure the voltage between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	PCM connector A (51P): disconnected
	PGM-FI main relay 1: disconnected
Test point 1	PGM-FI main relay 1 4P socket No. 3
Test point 2	Body ground

Is there battery voltage?


	YES

Go to step 14.


	NO

Repair an open in the +B IGP wire between PGM-FI main relay 1 and the No. B7 (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. B7 (15 A) fuse.?

14.

Open wire check (FI MAIN RLY CL- line):

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 (51P): disconnected
	PGM-FI main relay 1: disconnected
Test point 1	PGM-FI main relay 1 4P socket No. 4
Test point 2	PCM connector A (51P) No. 3

Is there continuity?


	YES

The FI MAIN RLY CL- wire is OK. Test PGM-FI main relay 1. If the relay is OK, update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away and the PCM was updated, troubleshooting is complete. 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 (A3) and PGM-FI main relay 1.?

15.

Open wire check (+B IGP line):

Open wire check (+B IGP line)

?1.	Remove PGM-FI main relay 1 (A) from the under-hood fuse/relay box.

?2.

Measure the voltage between test points 1 and 2.

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

Is there battery voltage?


	YES

Go to step 16.


	NO

Repair an open in the +B IGP wire between PGM-FI main relay 1 and No. B7 (15 A) fuse in the under-hood fuse/relay box.?

16.

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
	PCM connector A (51P): disconnected
	PGM-FI main relay 1: disconnected
Test point 1	PGM-FI main relay 1 4P socket No. 2
Test point 2	PCM connector A (51P) No. 5

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 PGM-FI main relay 1.?

17.

Relay check:

Relay check

?1.	Test PGM-FI main relay 1.

Is the relay OK?


	YES

PGM-FI main relay 1 is OK. Go to step 18.


	NO

Replace PGM-FI main relay 1.?

18.

Open wire check (PG2, PG3, LG lines):

Open wire check (PG2, PG3, LG lines)

?1.

Disconnect the following connectors.

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 B (51P): disconnected
	PCM connector C (51P): disconnected
	PGM-FI main relay 1: disconnected

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

Is there continuity?


	YES

The PG2, PG3, and LG wires are OK. Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away and the PCM was updated, troubleshooting is complete. If the symptom/indication goes away and the PCM was substituted, replace the original PCM.?


	NO

Repair an open in the PG2, PG3, or LG wire between the PCM (B11, B12, C1, C8) and G101.?