DTC F4 Side Sensor Bus LH Communication Error: 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: Side Sensor Bus LH Communication Error - Wiring Diagram

Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSTIC PROCEDURE CHART

Step	Check	Yes	No
1 CHECK POOR CONTACT OF CONNECTORS. Check for poor contact of the connectors (AB17, AB23, AB32) between the airbag control module and the curtain airbag sensor (LH).	Is there poor contact?	Replace the airbag rear harness along with body harness.	Go to step 2 .
2 CHECK AIRBAG REAR HARNESS (BETWEEN AIRBAG CONTROL MODULE AND SIDE AIRBAG SENSOR LH). Turn the ignition switch to OFF, disconnect the battery ground cable, and wait for 60 seconds or more. Disconnect the connector (AB21) from seat belt pretensioner (LH). Disconnect the connector (AB31) from curtain airbag module (LH). Disconnect connector (AB19) of the side airbag module (LH). Disconnect the connectors (AB17, AB6, AB18) from airbag control module. Connect the connector (1AG) in the test harness AG to the connectors (AB17, AB6, AB18). Disconnect the connector (AB23) from side airbag sensor (LH), and connect the connector (2V) in test harness V to connector (AB23). Measure the resistance between connector (5AG) in the test harness AG and connector (3V) in the test harness V. Connector & terminal (5AG) No. 10 - (3V) No. 1: (5AG) No. 8 - (3V) No. 2:	Is the resistance less than 10 Ω?	Go to step 3 .	Replace the airbag rear harness along with body harness.
3 CHECK AIRBAG REAR HARNESS (BETWEEN AIRBAG CONTROL MODULE AND SIDE AIRBAG SENSOR LH). Measure the resistance between connector (5AG) in the test harness AG and chassis ground, and the resistance between connector (5AG) terminals in the test harness AG. Connector & terminal (5AG) No. 10 - Chassis ground: (5AG) No. 8 - Chassis ground: (5AG) No. 10 - (5AG) No. 8:	Is the resistance 1 MΩ or more?	Go to step 4 .	Replace the airbag rear harness along with body harness.
4 CHECK AIRBAG REAR HARNESS (BETWEEN SIDE AIRBAG SENSOR LH AND CURTAIN AIRBAG SENSOR LH). Disconnect the connector (2V) in the test harness V from the connector (AB23) of side airbag sensor (LH). Connect the connector (AB23) of side air-bag sensor (LH) and the connector (1AI) in the test harness Al. Connect the connector (2AI) in the test harness Al and the connector (1V) in the test harness V. Disconnect the connector (AB32) from curtain airbag sensor (LH), and connect the connector (2V) in test harness V to connector (AB32). Measure the resistance between connector (3V) terminals in the test harness V. Connector & terminal (3V) No. 2 - (3V) No. 6: (3V) No. 1 - (3V) No. 7:	Is the resistance less than 10 Ω?	Go to step 5 .	Replace the airbag rear harness along with body harness.
5 CHECK AIRBAG REAR HARNESS (BETWEEN SIDE AIRBAG SENSOR LH AND CURTAIN AIRBAG SENSOR LH). Measure the resistance between connector (3V) in test harness V and chassis ground, and the resistance between connector (3V) in test harness V. Connector & terminal (3V) No. 2 - Chassis ground: (3V) No. 1 - Chassis ground: (3V) No. 2 - (3V) No. 1:	Is the resistance 1 MΩ or more?	Go to step 6 .	Replace the airbag rear harness along with body harness.
6 CHECK AIRBAG CONTROL MODULE. Connect all connectors. Clear the memory. Perform the Inspection Mode. Read the DTC.	Is the same DTC displayed?	Go to step 7 .	Go to step 8 .
7 REPLACE SIDE AIRBAG SENSOR (LH) AND CHECK AIRBAG CONTROL MODULE AFTER REPLACEMENT. Turn the ignition switch to OFF, disconnect the battery ground cable, and wait for 60 seconds or more. Replace the side airbag sensor (LH). < Ref. to REMOVAL , Side Airbag Sensor. > Connect all connectors. Clear the memory. Perform the Inspection Mode. Read the DTC.	Is the system normal?	Go to step 8 .	Replace the curtain airbag sensor (LH). < Ref. to REMOVAL , Curtain Airbag Sensor. > Replace the airbag control module if not operating normally even after replacing the sensor. < Ref. to REMOVAL , Airbag Control Module. >
8 CHECK FOR ANY OTHER DTC ON DISPLAY.	Is any other DTC displayed?	Check DTC using "List of Diagnostic Trouble Code (DTC)". < Ref. to LIST OF DIAGNOSTIC TROUBLE CODE (DTC) . >	Finish the diagnosis.