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

DTC DETECTING CONDITION:

• Open or power supply-output short, GND-output short occurs in both CAN line.

• Internal error in each control module

TROUBLE SYMPTOM:

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

WIRING DIAGRAM:

STEP	CHECK	YES	NO
1.CHECK DTC. Read the DTC of body integrated unit using Subaru Select Monitor.	Is U1302 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) Read the DTC of body integrated unit using Subaru Select Monitor.	Is U1302 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 (auto A/C): (i84) No. 9 — (i88) No. 19 (auto 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) Read the DTC of body integrated unit using Subaru Select Monitor.	Is U1302 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 in connector terminal?	Repair the connector terminal, or replace harness.	Temporary poor contact occurs.