LAN SYSTEM (DIAGNOSTICS) > Diagnostic Procedure with Diagnostic Trouble Code (DTC)

DTC U1221 CAN-HS ECM NO-RECEIVE DATA

DTC DETECTING CONDITION:

Defective ECM. (If error is in the main harness, DTC P0600 CAN communication link is input simultaneously.)

TROUBLE SYMPTOM:

Malfunction indicator light illuminates.

WIRING DIAGRAM:

• VDC model:

• ABS model

STEPCHECKYESNO

1.CHECK DTC.

Using the Subaru Select Monitor, read all DTCs.

Are there DTC U1201 or U1202?

Perform the diagnosis according to DTC.

2.CHECK DTC.

Read the DTC of body integrated unit using Subaru Select Monitor.

Is U1221 a current malfunction?

3.CHECK DTC.

1) Turn the ignition switch to OFF.

2) Disconnect all connectors (B280, B310 or B301, B55, B135 or B136, B230, B231) that are connected to high speed CAN communication line.

3) Connect the disconnected connectors.

4) Read the DTC of body integrated unit using Subaru Select Monitor.

Is U1221 a current malfunction?

4.CHECK CURRENT DATA.

1) Turn the ignition switch to OFF.

2) Disconnect all connectors (B280, B310 or B301, B55, B135 or B136, B230, B231) that are connected to high speed CAN communication line.

3) Using the tester, measure the resistance between terminals of harness.

Connector & terminal

VDC model:

(B40) No. 6 — (B135) No. 1 (non-turbo model):
(B40) No. 6 — (B136) No. 27 (turbo model):
(B40) No. 6 — (B310) No. 35:
(B40) No. 6 — (B230) No. 2:
(B40) No. 6 — (B231) No. 2:
(B40) No. 6 — (B55) No. 18:
(B40) No. 6 — (B280) No. 3:

ABS model

(B40) No. 6 — (B135) No. 1 (non-turbo model):
(B40) No. 6 — (B136) No. 27 (turbo model):
(B40) No. 6 — (B301) No. 26:
(B40) No. 6 — (B55) No. 18:
(B40) No. 6 — (B280) No. 3:

Is the resistance less than 10 Ω?

Repair or replace the open circuit of the harness.

5.CHECK HARNESS.

Using the tester, measure the resistance between terminals of harness.

Connector & terminal

VDC model:

(B40) No. 14 — (B135) No. 2 (non-turbo model):
(B40) No. 14 — (B136) No. 35 (turbo model):
(B40) No. 14 — (B310) No. 10:
(B40) No. 14 — (B230) No. 3:
(B40) No. 14 — (B231) No. 1:
(B40) No. 14 — (B55) No. 17:
(B40) No. 14 — (B280) No. 9:

ABS model

(B40) No. 14 — (B135) No. 2 (non-turbo model):
(B40) No. 14 — (B136) No. 35 (turbo model):
(B40) No. 14 — (B301) No. 11:
(B40) No. 14 — (B55) No. 17:
(B40) No. 14 — (B280) No. 9:

Is the resistance less than 10 Ω?

Repair or replace the open circuit of the harness.

6.CHECK DTC.

1) Turn the ignition switch to OFF.

2) Connect the disconnected connectors.

3) Read the DTC of body integrated unit using Subaru Select Monitor.

Is U1221 a current malfunction?

7.CHECK DTC.

Using the Subaru Select Monitor, read all DTCs.

Are DTCs P1718 or P0044, P0045, P0140 detected?

Replace the ECM.

Replace the body integrated unit.

8.CHECK HARNESS.

1) Turn the ignition switch to OFF.

2) Shake the harness used for CAN communication circuit.

3) Read the DTC of body integrated unit using Subaru Select Monitor.

Is U1221 a current malfunction?

Repair or replace the harness.

9.CHECK CONNECTOR.

1) Turn the ignition switch to OFF.

2) Disconnect all the connector that is connected to high speed CAN circuit.

Is there poor contact in connector terminal?

Repair the connector terminal where poor contact exists, or replace harness.

Temporary poor contact occurs.