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

DTC U1201 CAN-HS COUNTER ABNORMAL

DTC DETECTING CONDITION:

Communication is unstable because of high speed CAN communication error.

TROUBLE SYMPTOM:

Malfunction indicator light illuminates.

WIRING DIAGRAM:

• Gasoline engine model

• Diesel engine model

STEPCHECKYESNO

1.CHECK DTC.

Read all DTCs using the Subaru Select Monitor.

Are there U1202 or DTCs other than for the body integrated unit?

Perform the diagnosis according to DTC.

2.CHECK DTC.

Check DTC indicated by body integrated unit.

Is U1201 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 all the disconnected connectors.

4) Turn the ignition switch to ON.

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

Is U1201 a current malfunction?

4.CHECK POWER STEERING CM.

NOTE:

If the vehicle is equipped with hydraulic power steering, go to next.

1) Turn the ignition switch to OFF.

2) Disconnect the power steering CM connector (B450).

3) Turn the ignition switch to ON.

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

Is U1201 a current malfunction?

5.CHECK TCM.

NOTE:

If the vehicle is MT model, go to the next step.

1) Turn the ignition switch to OFF.

2) Disconnect the TCM connector (B55).

3) Turn the ignition switch to ON.

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

Is U1201 a current malfunction?

6.CHECK STEERING ANGLE SENSOR.

NOTE:

Model without VDC:

1) Turn the ignition switch to OFF.

2) Connect the TCM connector or the power steering CM connector.

3) Disconnect the steering angle sensor connector (B231).

4) Turn the ignition switch to ON.

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

Is U1201 a current malfunction?

7.CHECK YAW RATE SENSOR.

1) Turn the ignition switch to OFF.

2) Connect the steering angle sensor connector.

3) Disconnect the yaw rate sensor connector (B230).

4) Turn the ignition switch to ON.

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

Is U1201 a current malfunction?

8.CHECK VDC/ABS CM.

1) Turn the ignition switch to OFF.

2) Connect the yaw rate sensor connector.

3) Disconnect the VDC/ABS CM (B301 or B310) connector.

4) Install the 120 Ω resistance to VDC/ABS CM connector terminals.

Terminals

Models with VDC

(B310) No. 10 — No. 35:

Models without VDC

(B301) No. 11 — No. 26:

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

Terminals

(B40) No. 6 — No. 14:

Is the resistance 60 Ω?

9.CHECK DTC.

1) Turn the ignition switch to ON.

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

Is U1201 a current malfunction?

10.CHECK DTC.

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

Is U1202 a current malfunction?

Replace the VDC/ABS CM.

11.CHECK ECM.

1) Turn the ignition switch to OFF.

2) Connect the VDC/ABS CM.

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

4) Install the 120 Ω resistance to ECM connector.

Terminals

Gasoline engine model

(B135) No. 1 — No. 2:

Diesel engine model

(B134) No. 51 — No. 52:

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

Connector & terminal

(B40) No. 6 — No. 14:

Is the resistance 60 Ω?

Repair or replace the open circuit of harness.

12.CHECK DTC.

1) Turn the ignition switch to ON.

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

Is U1201 a current malfunction?

13.CHECK DTC.

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

Is U1202 a current malfunction?

Replace the ECM.

14.CHECK DTC.

1) Turn the ignition switch to OFF.

2) Reconnect all the disconnected connectors.

3) Turn the ignition switch to ON.

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

Is U1201 a current malfunction?

Replace the body integrated unit.

15.CHECK HARNESS.

1) Shake the instrument harness and bulkhead harness, rear harness.

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

Is U1201 a current malfunction?

Repair or replace the harness.

16.CHECK CONNECTOR.

1) Disconnect the connector used for CAN circuit.

2) Check the connector terminal.

Is there poor contact of connector terminal?

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

It is possible that temporary poor communication occurs.

17.CHECK HARNESS.

Using the tester, check for open or short (power supply-output short, GND-output short) in the harness between terminals of data link connector and power steering CM.

Connector & terminal

(B40) No. 14 — (B450) No. 7:
(B40) No. 6 — (B450) No. 6:

Is harness normal?

Replace the power steering CM.

Repair or replace the harness.

18.CHECK HARNESS.

Using the tester, check for open or short (power supply-output short, GND-output short) in the harness between terminals of data link connector and TCM.

Connector & terminal

(B40) No. 14 — (B55) No. 17:

(B40) No. 6 — (B55) No. 18:

Is harness normal?

Replace the TCM.

Repair or replace the harness.

19.CHECK HARNESS.

Using the tester, check for open or short (power supply-output short, GND-output short) in the harness between terminals of data link connector and steering angle sensor.

Connector & terminal

(B40) No. 14 — (B231) No. 1:

(B40) No. 6 — (B231) No. 2:

Is harness normal?

Replace the steering angle sensor.

Repair or replace the harness.

20.CHECK HARNESS.

Using the tester, check for open or short (power supply-output short, GND-output short) in the harness between terminals of data link connector and yaw rate sensor.

Connector & terminal

(B40) No. 14 — (B230) No. 3:

(B40) No. 6 — (B230) No. 2:

Is harness normal?

Replace the yaw rate sensor.

Repair or replace the harness.