Basic Diagnostic Procedure: Procedure

WARNING: This page is about a different car, the 2022 Subaru WRX. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION:

Remove foreign matter (dust, water, oil, etc.) from each control module connector during removal and installation.
Registration of immobilizer may be needed after the replacement of control modules, etc. For detailed procedure, refer to the "REGISTRATION MANUAL FOR IMMOBILIZER" provided as a separate volume.

NOTE:

To check harness for open or short circuits, shake the suspected trouble spot or connector.
Perform the diagnosis, and when the control module is replaced as a result of judgment that malfunction is the control module, re-check that the control module was actually malfunctioning. Replace to a new control module, and confirm that the malfunction is eliminated. Then, install the previously removed control module again and check that the malfunction reproduces again.

CHECK PRE-INSPECTION .
Ask the customer when and how the trouble occurred using the Check List for Interview. Ref. to LAN SYSTEM (DIAGNOSTICS)>CHECK LIST FOR INTERVIEW

Did you interview the customer?

Yes : Go to 2.

No : Perform the interview, and Go to 2.
BASIC INSPECTION (CAN DIAGNOSTIC IS NOT USED) .
Check the power supply circuit of the module which might affect CAN communication problem. Ref. to LAN SYSTEM (DIAGNOSTICS)>GENERAL DESCRIPTION>INSPECTION>INSPECTION WITHOUT USING CAN DIAGNOSTIC

Is the power supply circuit of each module that is performing CAN communication normal?

Yes : Go to 3.

No : Repair or replace the faulty portion, and Go to 3.
BASIC INSPECTION (CAN DIAGNOSTIC IS USED) .
Check the registration status of the body integrated unit which might affect CAN communication problem. Ref. to LAN SYSTEM (DIAGNOSTICS)>GENERAL DESCRIPTION>INSPECTION>INSPECTION USING CAN DIAGNOSTIC

Does the registration status of the body integrated unit match with the vehicle specification? (When the Subaru Select Monitor and the body integrated unit cannot communicate, and the registration status cannot be checked, Go to 5 . )

Yes : Go to 4.

No : Match the registration status of the body integrated unit with the vehicle specification, and Go to 4.
CHECK COMMUNICATION FOR INITIALIZING .
Communicate with the all systems by connecting the Subaru Select Monitor.

Is the communication for initializing finished for all modules?

Yes : Go to 5.

No : Check the error of communication for initializing. Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTIC PROCEDURE FOR SUBARU SELECT MONITOR COMMUNICATION>INSPECTION
CHECK DTC .
1. Start the engine and read all DTCs. Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)
  NOTE:
  - When the engine does not start, perform the diagnosis for the engine start malfunction. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>DIAGNOSTICS WITH PHENOMENON
  - For detailed operation procedures, refer to "Help" of application.
2. Record all DTCs (current code and history code), time stamp and freeze frame data.
  NOTE:
  For time stamp, refer to "TIME STAMP" of COMMON (DIAGNOSTICS). Ref. to COMMON (DIAGNOSTICS)>TIME STAMP
Is DTC displayed on Subaru Select Monitor? (Current code)

Yes : Go to 6.

No : Perform diagnosis according to the procedures in the diagnostics with phenomenon. Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTICS WITH PHENOMENON
CHECK DTC .
Check the displayed DTC.

Is DTC B1E01, U1E**, U1C**, U1D**, or another U*** displayed?

Yes : Go to 7.

No : Perform the diagnosis of the displayed DTCs other than B1E01, U1E**, U1C**, U1D**, or other U****.
CHECK DTC .
Check the displayed DTC.

When only DTC B1E01 is displayed, go to A.

When only DTC U1E** is displayed, go to B.

When only DTC U1C** is displayed, go to C.

When only DTC U1D** is displayed, go to D.

When U**** other than the above is displayed, go to E.

When multiple DTCs above are displayed, go to F.
1. Perform the diagnosis for the displayed DTCs. Ref. to CENTRAL GATEWAY (DIAGNOSTICS)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)>DTC B1E01 UNREGISTERED OF AUTHENTICATION UNIT
2. Perform the diagnosis for the displayed DTCs. Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST
3. Perform the diagnosis for the displayed DTCs. Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST
4. Perform the diagnosis for the displayed DTCs. Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST
5. Go to 8.
6. Perform the diagnosis in the following priority order.
1. DTC B1E01: Ref. to CENTRAL GATEWAY (DIAGNOSTICS)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)>DTC B1E01 UNREGISTERED OF AUTHENTICATION UNIT
2. DTC U1C**: Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST
3. DTC U1D**: Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST
4. DTC U1E**: Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST
5. DTC U**** other than above: Go to 8.
CHECK USING THE DTC CHECK SHEET .
Perform the inspection using the DTC check sheet. Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST>CHECK USING THE DTC CHECK SHEET

Is CAN communication line faulty?

Yes : Repair or replace the faulty portion of the harness. And then, Go to 9.

No : Perform the diagnosis for the displayed DTCs. And then, Go to 9.
PERFORM DIAGNOSIS .
1. Using the Subaru Select Monitor, perform the clear memory of all DTCs. Ref. to COMMON (DIAGNOSTICS)>CLEAR MEMORY
2. Start the engine and read all DTCs. Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)
Are any DTCs displayed? (Current code)

Yes : Repeat the Basic Diagnostic Procedure from the beginning until DTC is not shown.

No : Finish the diagnosis.