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

DTC U1202 CAN-HS BUS OFF

DTC DETECTING CONDITION:

Integrated unit communication is shut down because of high speed CAN error.

TROUBLE SYMPTOM:

CAN communication is not normal.

WIRING DIAGRAM:

• Gasoline engine model

• Diesel engine model

STEPCHECKYESNO

1.CHECK DTC.

Using the Subaru Select Monitor, confirm all DTCs.

Is any DTC other than for the body integrated unit displayed?

Perform the diagnosis according to displayed DTC.

2.CHECK DTC.

1) Turn the ignition switch to OFF → ON.

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

Is U1202 a current malfunction?

3.CHECK DTC.

1) Turn the ignition switch to OFF.

2) Disconnect all connectors (B280, B310 or B301, B55, B134 or B135, B230, B231, B450) that are connected to high speed CAN communication line.

3) Connect the disconnected connectors.

4) Turn the ignition switch to ON.

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

Is U1202 a current malfunction?

4.CHECK HARNESS.

1) Turn the ignition switch to OFF.

2) Disconnect all connectors (B280, B310 or B301, B55, B134 or B135, B230, B231) that are connected to high speed CAN communication line.

3) Using the tester, check for open, short (power supply-output short, GND-output short) in the harness.

Connector & terminal

Models with VDC

(B40) No. 6 — (B135) No. 1 (gasoline engine model):
(B40) No. 6 — (B134) No. 51 (diesel engine 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 (AT model):
(B40) No. 6 — (B280) No. 3:
(B40) No. 6 — (B450) No. 6 (diesel engine model):

Models without VDC

(B40) No. 6 — (B135) No. 1:
(B40) No. 6 — (B301) No. 26:
(B40) No. 6 — (B55) No. 18 (AT model):
(B40) No. 6 — (B280) No. 3:

Is harness normal?

Repair or replace the harness.

5.CHECK HARNESS.

Using the tester, check for open, short (power supply-output short, GND-output short) in the harness.

Connector & terminal

Models with VDC

(B40) No. 14 — (B135) No. 2 (gasoline engine model):
(B40) No. 14 — (B134) No. 52 (diesel engine 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 (AT model):
(B40) No. 14 — (B280) No. 9:
(B40) No. 14 — (B450) No. 7 (diesel engine model):

Models without VDC

(B40) No. 14 — (B135) No. 2:
(B40) No. 14 — (B301) No. 11:
(B40) No. 14 — (B55) No. 17 (AT model):
(B40) No. 14 — (B280) No. 9:

Is harness normal?

Repair or replace the harness.

6.CHECK ECM.

1) Connect the ECM.

2) Using the tester, measure the resistance between terminals of data link connector.

Connector & terminal

(B40) No. 6 — No. 14:

Is the resistance 120±5 Ω?

Replace the ECM.

7.CHECK VDC/ABS CM.

1) Disconnect the ECM connector (B134 or B135).

2) Connect the VDC/ABS CM.

3) Using the tester, measure the resistance between terminals of data link connector.

Connector & terminal

(B40) No. 6 — No. 14:

Is the resistance 120±5 Ω?

Replace the VDC/ABS CM.

8.CHECK HARNESS.

1) Connect the disconnected connectors.

2) Using the tester, measure the resistance between terminals of data link connector and chassis ground.

Connector & terminal

(B40) No. 6 — Chassis ground:
(B40) No. 14 — Chassis ground:

Is the resistance 1 MΩ or more?

9.CHECK HARNESS.

1) Turn the ignition switch to ON.

2) Using the tester, measure the voltage between terminals of data link connector and chassis ground.

Connector & terminal

(B40) No. 6 (+) — Chassis ground (−):
(B40) No. 14 (+) — Chassis ground (−):

Is the voltage less than 6 V?

Replace the body integrated unit.

10.CHECK HARNESS.

1) Shake the harness.

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

Is U1202 a current malfunction?

Repair or replace the harness.

11.CHECK CONNECTOR.

Disconnect the connector used for high speed CAN circuit.

Is there poor contact of connector terminal?

Repair the connector terminal, or replace harness.

It is possible that temporary poor communication occurs.

12.CHECK CONTROL MODULE.

With the tester connected, disconnect each control module connector.

Is there any control module whose resistance has changed?

Replace the control module whose resistance has changed.

Repair or replace the open or short circuit of the harness.

13.CHECK ECM.

With the tester connected, disconnect each control module connector.

Is there any control module whose voltage has changed?

Replace the control module whose voltage has changed.

Repair or replace the short circuit of the harness.