DTC P1621 (Flash Code 54) Control Module Long Term Memory Performance (RZ4E-TC)

1. Engine control system check

Refer to "51.Engine Control 1A.Troubleshooting(RZ4E-TC) Diagnostic system check-engine controls".

2. Current DTC check

1) Connect the scan tool.

2) Turn OFF the ignition switch for 30 seconds or more.

3) Turn ON the ignition switch.

4) Observe the DTC information with a scan tool. Is a DTC set?

Yes

=>Go to Injector ID code upload.

No

=>Go to Repair verification.

3. Injector ID code upload

Caution

  • Upload the Injector ID Code in the ECM to the scan tool before clearing the EEPROM error.
  • The scan tool must be same from start to finish. If the scan tool is changed midway, information cannot be written correctly.

1) Turn ON the ignition switch.

2) Select the scan tool item.

  • Diagnostics
  • Engine
  • RZ4E
  • Programming
  • Injector ID Code
  • Upload Injector ID

3) Follow the directions on the screen and upload the injector ID codes to a scan tool.

4) After completing the upload, turn OFF the ignition switch.

Procedure completion

=>Go to EEPROM Error Clear.

4. EEPROM Error Clear

1) Turn ON the ignition switch.

2) Select the scan tool item.

  • Diagnostics
  • Engine
  • RZ4E
  • Special Function
  • EEPROM Error Clear

3) Perform EEPROM Error Clear by following the on-screen instructions.

4) After the EEPROM Error Clear, turn OFF the ignition switch for 1 minute.

Procedure completion

=>Go to VIN programming.

5. VIN programming

1) Turn ON the ignition switch.

2) Select the scan tool item.

  • Diagnostics
  • Engine
  • RZ4E
  • Programming
  • Program VIN (Vehicle Identification Number)

3) Program the VIN into the ECM by following the on-screen instructions.

Note

  • If the VIN does not display or is not correct, input the correct VIN.

4) After completing the programming, turn OFF the ignition switch for 1 minute.

Procedure completion

=>Go to Injector ID Code download.

6. Injector ID Code download

1) Turn ON the ignition switch.

2) Select the scan tool item.

  • Diagnostics
  • Engine
  • RZ4E
  • Programming
  • Injector ID Code
  • Download Injector ID

3) Follow the directions on the screen and download the injector ID codes to the ECM.

4) After completing the download, turn OFF the ignition switch for 1 minute.

Procedure completion

=>Go to Injector ID Code verification.

7. Injector ID Code verification

1) Turn ON the ignition switch.

2) Perform Program Injector ID Code with a scan tool.

3) Make sure that the Injector ID Code on the display matches the vehicle Injector ID Code.

4) If the injector ID codes do not display or are not correct, input the correct injector ID codes.

Procedure completion

=>Go to Fuel Supply Pump Relearning.

8. Fuel Supply Pump Relearning

1) Turn ON the ignition switch.

2) Select the scan tool item.

  • Diagnostics
  • Engine
  • RZ4E
  • Special Function
  • Fuel Supply Pump Learn Resetting

3) Reset the Fuel Supply Pump Learning by following the on-screen instructions.

4) Observe that the Fuel Supply Pump Learning Status parameter changes to Not Learned on the scan tool Data Display.

5) Start and completely warm up the engine until the engine coolant temperature reaches 65°C {149°F} or more.

6) Observe the Fuel Supply Pump Learning Status parameter on the scan tool.

7) The procedure is complete when the parameter changes from Not Learned to Learned.

Procedure completion

=>Go to Programming verification.

9. Programming verification

1) Turn OFF the ignition switch for 30 seconds or more.

2) Turn ON the ignition switch.

3) Observe the DTC information with a scan tool. Is a DTC set?

Yes

=>Go to ECM replacement.

No

=>Go to Repair verification.

10. ECM replacement

Note

  • Perform programming after replacing the ECM.

Refer to "1.Engine 1Z.Engine Electrical Control(RZ4E-TC) ECM removal".

Refer to "1.Engine 1Z.Engine Electrical Control(RZ4E-TC) ECM installation".

Refer to "1.Engine 1Z.Engine Electrical Control(RZ4E-TC) ECM setting".

Procedure completion

=>Go to Repair verification.

11. Repair verification

1) Clear the DTC with a scan tool.

2) Turn OFF the ignition switch for 30 seconds or more.

3) Start the engine.

4) Observe the DTC information with a scan tool.