ECM Power and Ground Circuit Troubleshooting

Engine

ECM Power and Ground Circuit Troubleshooting

ECM 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 Component Tests and General Diagnostics.
-NO- Go to step 2.

2. Determine possible failure area (+B_IG_MAIN wire shorted, others):

Determine possible failure area (+B_IG_MAIN wire shorted, others):
-1. Turn the ignition switch to LOCK (0).

-2. Check the following fuse.





Is the fuse OK?
-YES- Repair open in the +B_IG_MAIN wire between the No. A2-1 (50 A) fuse and the ignition switch. If the wire is OK, go to step 3.
-NO- Repair a short in the +B_IG_MAIN wire between the No. A2-1 IG MAIN (50 A) fuse and the under-hood fuse/relay box. Also replace the No. A2-1 IG MAIN (50 A) fuse.

3. Fuse check:

Fuse check
-1. Check the following fuse.





Is the fuse OK?
-YES- Go to step 8.
-NO- Go to step 4.

4. Determine possible failure area (+B_IGP line, others):

Determine possible failure area (+B_IGP line, others)
-1. Remove the blown No. A21 (15 A) fuse from the under-hood fuse/relay box.

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





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














Is there continuity?
-YES- Go to step 5.
-NO- Go to step 6.

5. Shorted wire check (+B_IGP line):

Shorted wire check (+B_IGP line)
-1. Disconnect the following connector.





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









Is there continuity?
-YES- Repair a short the +B_IGP wire between the No. A21 (15A) fuse and the under-dash fuse/relay box. Also replace the No. A21 (15A) fuse.
-NO- The +B_IGP wire is OK. Replace the under-hood fuse/relay box. Also replace the No. A21 (15 A) fuse.

6. 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. 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
* ECM connector A (49P)
* Each injector 2P connector
* CMP sensor B 3P connector
* CKP sensor 3P connector
* Electronic throttle control system (ETCS) control relay









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 ECM, update the ECM ECM/PCM Update if it does not have the latest software, or substitute a known-good ECM Service and Repair, then recheck. If the symptom/indication goes away and the ECM was updated, troubleshooting is complete. If the symptom/indication goes away and the ECM was substituted, replace the original ECM Service and Repair. Also replace the No. A21 (15 A) fuse.
-NO- Parts are OK. Go to step 7.

7. Shorted wire check (FI_MAIN_RLY_OUT line):

Shorted wire check (FI_MAIN_RLY_OUT line)
-1. Disconnect the following parts:
* PGM-FI main relay 2
* ECM connector A (49P)
* Injectors
* CMP sensor B
* CKP sensor
* Electronic throttle control system (ETCS) control relay

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









Does continuity go away when one of the above components is disconnected?
-YES- Repair a short in the FI_MAIN_RLY_OUT wire between PGM-FI main relay 1 and each part. Also replace the No. A21 (15 A) fuse.
-NO- Replace PGM-FI main relay 1. Also replace the No. A21 (15 A) fuse.

8. Fuse check 2:

Fuse check 2
-1. Check the following fuse.





Is the fuse OK?
-YES- Go to step 13.
-NO- Go to step 9.

9. Relay check:

Relay check
-1. Remove the blown No. B4 (15 A) fuse from the under-hood 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. Testing and Inspection

Is the relay OK?
-YES- PGM-FI main relay 2 is OK. Go to step 10.
-NO- Replace PGM-FI main relay 2. Also replace the No. B4 (15 A) fuse.

10. 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.









Is there continuity?
-YES- Go to step 11.
-NO- Go to step 12.

11. Shorted wire check (IG1 line):

Shorted wire check (IG1 line)
-1. Jump the SCS line with the HDS.

-2. Disconnect the following connector.





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









Is there continuity?
-YES- Repair a short in the IG1 wire between the No. B4 (15 A) fuse and the ECM (C10), between the No. B4 (15 A) fuse and PGM-FI main relay 2, or between the No. B4 (15 A) fuse and the immobilizer control unit. Also replace the No. B4 (15 A) fuse.
-NO- Replace the No. B4 (15 A) fuse, and update the ECM ECM/PCM Update if it does not have the latest software, or substitute a known-good ECM Service and Repair, then recheck. If the symptom/indication goes away and the ECM was updated, troubleshooting is complete. If the symptom/indication goes away and the ECM was substituted, replace the original ECM Service and Repair.

12. Shorted wire check (FUEL_PUMP_RLY_OUT line):

Shorted wire check (FUEL_PUMP_RLY_OUT line)
-1. Remove the access panel from the floor.

-2. Disconnect the following connector.





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









Is there continuity?
-YES- Repair a short in the FUEL_PUMP_RLY_OUT wire between the fuel tank unit 4P connector and PGM-FI main relay 2. Also replace the No. B4 (15 A) fuse.
-NO- Check the fuel pump, and replace it if needed. Also replace the No. B4 (15 A) fuse.

13. Open wire check (IG1 line):

Open wire check (IG1 line)
-1. Jump the SCS line with the HDS.

-2. Disconnect the following connectors.





-3. Turn the ignition switch to ON (II).

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









Is there battery voltage?
-YES- The IG1 wire is OK. Go to step 14.
-NO- Repair an open in the IG1 wire between the No. B4 (15 A) fuse and the ECM (C10).

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









Is there battery voltage?
-YES- Go to step 18.
-NO- Go to step 15.

15. Determine possible failure area (+B_IGP line, others):

Determine possible failure area (+B_IGP line, others)
-1. Turn the ignition switch to LOCK (0).

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





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









Is there battery voltage?
-YES- Go to step 17.
-NO- Go to step 16.

16. Open wire check (+B_IGP line):

Open wire check (+B_IGP line)
-1. Disconnect the following connector.





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









Is there battery voltage?
-YES- The +B_IGP wire is OK. Replace the under-hood fuse/relay box.
-NO- Repair an open the +B_IGP wire between the No. A21 (15A) fuse and the under-dash fuse/relay box.

17. 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.









Is there continuity?
-YES- The FI_MAIN_RLY_CL- wire is OK. Test PGM-FI main relay 1 Testing and Inspection. If the relay is OK, update the ECM ECM/PCM Update if it does not have the latest software, or substitute a known-good ECM Service and Repair, then recheck. If the symptom/indication goes away and the ECM was updated, troubleshooting is complete. If the symptom/indication goes away and the ECM was substituted, replace the original ECM Service and Repair.
-NO- Repair an open in the FI_MAIN_RLY_CL- wire between the ECM (A7) and PGM-FI main relay 1.

18. Determine possible failure area (+B_IGP line, others):

Determine possible failure area (+B_IGP line, others)
-1. Turn the ignition switch to LOCK (0).

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





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









Is there battery voltage?
-YES- Go to step 20.
-NO- Go to step 19.

19. Open wire check (+B_IGP line):

Open wire check (+B_IGP line)
-1. Disconnect the following connector.





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









Is there battery voltage?
-YES- The +B_IGP wire is OK. Replace the under-hood fuse/relay box.
-NO- Repair an open the +B_IGP wire between the No. A21 (15A) fuse and the under-dash fuse/relay box.

20. 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.









Is there continuity?
-YES- The FI_MAIN_RLY_OUT wire is OK. Go to step 21.
-NO- Repair an open in the FI_MAIN_RLY_OUT wire between the ECM (A9) and PGM-FI main relay 1.

21. Relay check:

Relay check
-1. Test PGM-FI main relay 1. Testing and Inspection

Is PGM-FI main relay 1 OK?
-YES- PGM-FI main relay 1 is OK. Go to step 22.
-NO- Replace PGM-FI main relay 1.

22. Open wire check (PG1, LG2 lines):

Open wire check (PG1, LG2 lines)
-1. Disconnect the following connector.





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


















Is there continuity?
-YES- The PG1/LG2 wires are OK. Update the ECM ECM/PCM Update if it does not have the latest software, or substitute a known-good ECM Service and Repair, then recheck. If the symptom/indication goes away and the ECM was updated, troubleshooting is complete. If the symptom/indication goes away and the ECM was substituted, replace the original ECM Service and Repair.
-NO- Repair an open in the PG1/LG2 wire between the ECM (B1, B20, C2, C15, C20) and G101.