DTC U1202 Can-HS Bus Off: Wiring Diagram

WARNING: This page is about a different car, the 2012 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: CAN-HS BUS Wiring Diagram

Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSTIC PROCEDURE CHART

Step	Check	Yes	No
1 CHECK DTC. Using the Subaru Select Monitor, confirm all DTCs. < Ref. to OPERATION , Subaru Select Monitor. >	Is any DTC other than for the body integrated unit displayed?	Perform the diagnosis according to displayed DTC.	Go to step 2 .
2 CHECK DTC. Turn the ignition switch to OFF → ON. Read the DTC of body integrated unit using Subaru Select Monitor.	Is U1202 a current malfunction?	Go to step 3.	Go to step 10 .
3 CHECK DTC. Turn the ignition switch to OFF. Disconnect all control module connectors (B280, B310, B55, B136, B230, B231) that are connected to high speed CAN communication line. Connect the disconnected connectors. Turn the ignition switch to ON. Read the DTC of body integrated unit using Subaru Select Monitor.	Is U1202 a current malfunction?	Go to step 4.	Go to step 10 .
4 CHECK HARNESS. Turn the ignition switch to OFF. Disconnect all control module connectors (B280, B310, B55, B136, B230, B231) that are connected to high speed CAN communication line. Using the tester, check for open, short (power supply-output short, GND-output short) harness. Connector & terminal (B40) No. 6 - (B136) No. 17: (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:	Is harness normal?	Go to step 5.	Repair or replace the harness.
5 CHECK HARNESS. Using the tester, check for open, short (power supply-output short, GND-output short) harness. Connector & terminal (B40) No. 14 - (B136) No. 28: (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:	Is harness normal?	Go to step 6.	Repair or replace the harness.
6 CHECK ECM. Connect the ECM. 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?	Go to step 7.	Replace the ECM. < Ref. to REMOVAL , Engine Control Module (ECM). >
7 CHECK VDC/ABS CM. Disconnect the ECM connector (B136). Connect the VDC/ABS CM. 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?	Go to step 8.	Replace the VDC/ABS CM. < Ref. to REMOVAL , VDC Control Module and Hydraulic Control Unit (VDCCM&H/U). >
8 CHECK HARNESS. Connect the disconnected connectors. 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?	Go to step 9.	Go to step 12 .
9 CHECK HARNESS. Turn the ignition switch to ON. 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. < Ref. to REMOVAL , Body Integrated Unit. >	Go to step 13 .
10 CHECK HARNESS. Shake the harness. Read the DTC of body integrated unit using Subaru Select Monitor.	Is U1202 a current malfunction?	Repair or replace the harness.	Go to step 11 .
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.