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

DTC U1302 CAN-LS BUS OFF

DTC DETECTING CONDITION:

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

TROUBLE SYMPTOM:

Control modules which prevent the low speed CAN circuit communication are disconnected.

WIRING DIAGRAM:

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1.CHECK DTC.

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

Is U1302 a current malfunction?

2.CHECK DTC.

1) Turn the ignition switch to OFF.

2) Disconnect all connectors (i84, i10, i88, i85 or i50, B419) that are connected to low 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 U1302 a current malfunction?

3.CHECK HARNESS.

1) Disconnect all connectors (i84, i10, i88, i85 or i50, B419) that are connected to low speed CAN communication line.

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

Connector & terminal

(i84) No. 1 — (i10) No. 27 (combination meter):
(i84) No. 9 — (i10) No. 26 (combination meter):
(i84) No. 1 — (i88) No. 20 (A/C):
(i84) No. 9 — (i88) No. 19 (A/C):
(i84) No. 1 — (i85) No. 12 (audio):
(i84) No. 9 — (i85) No. 11 (audio):
(i84) No. 1 — (i50) No. 18 (navigation):
(i84) No. 9 — (i50) No. 6 (navigation):
(i84) No. 1 — (B419) No. 5 (gateway CM):
(i84) No. 9 — (B419) No. 4 (gateway CM):

Is the resistance less than 10 Ω?

Repair or replace the harness.

4.CHECK HARNESS.

1) Turn the ignition switch to OFF.

2) Connect the disconnected connectors.

3) Using the tester, measure the resistance between harness connector and chassis ground.

Connector & terminal

(i84) No. 1 — Chassis ground:

(i84) No. 9 — Chassis ground:

Is the resistance 1 MΩ or more?

5.CHECK HARNESS.

1) Turn the ignition switch to ON.

2) Using the tester, measure the voltage between harness connector and chassis ground.

Connector & terminal

(i84) No. 1 (+) — Chassis ground (−):

(i84) No. 9 (+) — Chassis ground (−):

Is the voltage less than 6 V?

Replace the body integrated unit.

6.CHECK HARNESS.

With the tester connected, disconnect control module.

Is there any control module that the voltage becomes 6 V or less.

Replace the control module whose voltage has changed.

Repair or replace the short circuit of the harness.

7.CHECK HARNESS.

With the tester connected, disconnect control module.

Is there any control module whose resistance has changed?

Replace the control module whose resistance has changed.

Repair or replace the short circuit of the harness.

8.CHECK HARNESS.

1) Shake the harness used for low speed CAN communication circuit.

2) Turn the ignition switch to ON.

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

Is U1302 a current malfunction?

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

9.CHECK CONNECTOR.

1) Turn the ignition switch to OFF.

2) Disconnect all connectors (i84, i10, i88, i85 or i50, B419) that are connected to low speed CAN communication line.

Is there poor contact of connector terminal?

Repair the connector terminal, or replace harness.

Temporary poor contact occurs.