P0603

P0603 ECM Power Supply

Component 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.





On Board Diagnosis Logic






DTC Confirmation Procedure

1) If DTC Confirmation Procedure has been previously conducted, always perform the following procedure before conducting the next step.
a) Turn ignition switch OFF and wait at least 10 seconds.
b) Turn ignition switch ON.
c) Turn ignition switch OFF and wait at least 10 seconds.
2) Turn ignition switch ON, wait at least 10 seconds.
3) Turn ignition switch OFF, wait at least 5 minutes.
4) Turn ignition switch ON, wait at least 10 seconds.
5) Repeat steps 2 to 3 for 5 times.
6) Check 1st trip DTC.
7) If 1st trip DTC is detected, go to "Diagnosis Procedure".

Diagnosis Procedure

1. CHECK ECM POWER SUPPLY

1 Turn ignition switch OFF.
2 Disconnect ECM harness connector.
3 Check voltage between ECM terminal 121 and ground with SDT or tester.











OK or NG
OK
GO TO 3.
NG
GO TO 2.

2. DETECT MALFUNCTIONING PART

Check the following.
- 20 A fuse (No.53)
- IPDM E/R harness connector E121
- Harness for open or short between ECM and battery


Repair open circuit in harness or connectors.

3. CHECK INTERMITTENT INCIDENT

Refer to [Service Information for Electrical Incident: Intermittent Incident] Service Information for Electrical Incident: Intermittent Incident.

OK or NG
OK
GO TO 4.
NG
Repair or replace harness or connectors.

4. PERFORM DTC CONFIRMATION PROCEDURE

With SDT
1 Turn ignition switch ON.
2 Select "DTC check" mode with SDT.
3 Touch "Clear".
4 Perform DTC Confirmation Procedure.
See "DTC Confirmation Procedure".
5 Is the 1st trip DTC P0603 displayed again?
With GST
1 Turn ignition switch ON.
2 Select Service $04 with GST.
3 Perform DTC Confirmation Procedure.
See "DTC Confirmation Procedure".
4 Is the 1st trip DTC P0603 displayed again?

Yes or No
Yes
GO TO 5.
No
INSPECTION END

5. REPLACE ECM

1 Replace ECM.
2 Perform initialization of immobilizer system and registration of all immobilizer system ignition key IDs. Refer to [Additional Service When Replacing Control Unit: Special Repair Requirement] Additional Service When Replacing Control Unit Special Repair Requirement.
3 Perform [VIN Registration] VIN Registration.
4 Perform [Accelerator Pedal Released Position Learning] Testing and Inspection.
5 Perform [Throttle Valve Closed Position Learning] Throttle Valve Closed Position Learning.
6 Perform [Idle Air Volume Learning] Idle Air Volume Learning.


INSPECTION END