Nissan Altima 2007-2012 Service Manual: P0603 ECM Power supply

Description

Battery voltage is supplied to the ECM even when the ignition switch is turned OFF for the ECM memory function of the DTC memory, the air-fuel ratio feedback compensation value memory, the idle air volume learning value memory, etc.

DTC Logic

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always perform the following before conducting the next test.

1. Turn ignition switch OFF and wait at least 10 seconds.

2. Turn ignition switch ON.

3. Turn ignition switch OFF and wait at least 10 seconds.

>> GO TO 2.

2.PERFORM DTC CONFIRMATION PROCEDURE

1. Turn ignition switch ON and wait at least 1 second.

2. Start engine and let it idle for 1 second.

3. Turn ignition switch OFF, wait at least 10 seconds, and then turn it ON.

4. Repeat steps 2 and 3 for 4 times.

5. Check 1st trip DTC.

Is 1st trip DTC detected? YES >> Go to EC-1374, "Diagnosis Procedure".

NO >> INSPECTION END

Diagnosis Procedure

1.CHECK ECM POWER SUPPLY

1. Turn ignition switch OFF.

2. Disconnect ECM harness connector.

3. Check the voltage between ECM harness connector and ground.

Is the inspection result normal? YES >> GO TO 3.

NO >> GO TO 2.

2.DETECT MALFUNCTIONING PART

Check the following.

• 15 A fuse (No. 42) • IPDM E/R harness connector F10

• Harness for open or short between ECM and battery

>> Repair or replace harness or connectors.

3.CHECK INTERMITTENT INCIDENT

Refer to GI-42, "Intermittent Incident".

Is the inspection result normal? YES >> GO TO 4.

NO >> Repair or replace harness or connectors.

4.PERFORM DTC CONFIRMATION PROCEDURE

1. Turn ignition switch ON.

2. Erase DTC.

3. Perform DTC CONFIRMATION PROCEDURE.

See EC-1374, "DTC Logic".

Is the 1st trip DTC P0603 displayed again? YES >> GO TO 5.

NO >> INSPECTION END

5.REPLACE ECM

1. Replace ECM.

2. Go to EC-1051, "ADDITIONAL SERVICE WHEN REPLACING CONTROL UNIT : Special Repair Requirement".

>> INSPECTION END

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