Subaru Legacy BN/BS (2015-2019) Service Manual: Dtc b1637 curtain airbag sensor lh lost communication

Subaru Legacy BN/BS (2015-2019) Service Manual / Airbag system (diagnostics) / Diagnostic chart with trouble code / Dtc b1637 curtain airbag sensor lh lost communication

DIAGNOSIS START CONDITION:

Ignition voltage is 10 V to 16 V.

DTC DETECTING CONDITION:

Curtain airbag sensor LH communication error (open/short circuit or connector connection failure between airbag CM and sensor, sensor internal communication circuit failure, CM internal communication circuit failure)

CAUTION:

Before performing diagnosis, refer to “CAUTION” in “General Description”. General Description > CAUTION

WIRING DIAGRAM:

NOTE:

For the coupling connector, refer to “WIRING SYSTEM”.

Airbag system Airbag System > WIRING DIAGRAM

STEP	CHECK	YES	NO
1.CHECK DTC. Read the DTC. (Current malfunction) Read Diagnostic Trouble Code (DTC)	Is DTC B1637 displayed-	Perform the diagnosis according to DTC.	Diagnostic Chart with Trouble Code > DTC B1637 CURTAIN AIRBAG SENSOR LH LOST COMMUNICATION
2.CHECK POOR CONTACT OF CONNECTORS. Check for poor contact of the connectors between the airbag control module and the door sensor LH.	Is there poor contact-	Replace the airbag rear harness and the door harness.	Diagnostic Chart with Trouble Code > DTC B1637 CURTAIN AIRBAG SENSOR LH LOST COMMUNICATION
3.CHECK AIRBAG REAR HARNESS (BETWEEN SIDE AIRBAG SENSOR LH AND CURTAIN AIRBAG SENSOR LH) (OPEN CIRCUIT). 1) Turn the ignition switch to OFF, disconnect the battery ground cable, and wait for 60 seconds or more. 2) Disconnect the connector (AB21) from seat belt pretensioner LH. 3) Disconnect the connector (AB5) from seat cushion airbag module LH. 4) Disconnect the connector (AB31) from curtain airbag module LH. 5) Disconnect the connector (AB19) of the side airbag module LH. 6) Disconnect the connector (AB23) in the side airbag sensor LH. 7) Connect the connector (AB23) of side airbag sensor LH and the connector (1AI) in the test harness AI. 8) Connect the connector (2AI) in the test harness AI and the connector (1V) in the test harness V. 9) Disconnect the connector (AB32) from curtain airbag sensor LH, and connect it to the connector (2V) in test harness V. 10) 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 --	Diagnostic Chart with Trouble Code > DTC B1637 CURTAIN AIRBAG SENSOR LH LOST COMMUNICATION	Replace the airbag rear harness along with body harness.
4.CHECK AIRBAG REAR HARNESS (BETWEEN SIDE AIRBAG SENSOR AND CURTAIN AIRBAG SENSOR LH) (SHORTED TO GROUND AND SHORTED BETWEEN LINES). 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. 1 — Chassis ground: (3V) No. 2 — Chassis ground: (3V) No. 1 — (3V) No. 2:	Is the resistance 1 M- or more-	Diagnostic Chart with Trouble Code > DTC B1637 CURTAIN AIRBAG SENSOR LH LOST COMMUNICATION	Replace the airbag rear harness along with body harness.
5.CHECK AIRBAG CONTROL MODULE. 1) Connect all connectors. 2) Clear the memory. Clear Memory Mode 3) Perform the Inspection Mode. Inspection Mode 4) Read the DTC. (Current malfunction) Read Diagnostic Trouble Code (DTC)	Is DTC B1637 displayed-	Diagnostic Chart with Trouble Code > DTC B1637 CURTAIN AIRBAG SENSOR LH LOST COMMUNICATION	Diagnostic Chart with Trouble Code > DTC B1637 CURTAIN AIRBAG SENSOR LH LOST COMMUNICATION
6.CHECK CURTAIN AIRBAG SENSOR LH. 1) Turn the ignition switch to OFF, disconnect the battery ground cable, and wait for 60 seconds or more. 2) Replace the curtain airbag sensor LH by the curtain airbag sensor RH. Curtain Airbag Sensor > REMOVAL 3) Connect all connectors. 4) Clear the memory. Clear Memory Mode 5) Perform the Inspection Mode. Inspection Mode 6) Read the DTC. (Current malfunction) Read Diagnostic Trouble Code (DTC)	Is DTC B1637 displayed-	Diagnostic Chart with Trouble Code > DTC B1637 CURTAIN AIRBAG SENSOR LH LOST COMMUNICATION	Replace the curtain airbag sensor LH. Curtain Airbag Sensor > REMOVAL
7.CHECK SIDE AIRBAG SENSOR LH. 1) Turn the ignition switch to OFF, disconnect the battery ground cable, and wait for 60 seconds or more. 2) Restore the curtain airbag sensors LH and RH back to their original position. Curtain Airbag Sensor > REMOVAL 3) Replace the side airbag sensor LH by the side airbag sensor RH. Side Airbag Sensor > REMOVAL 4) Connect all connectors. 5) Clear the memory. Clear Memory Mode 6) Perform the Inspection Mode. Inspection Mode 7) Read the DTC. (Current malfunction) Read Diagnostic Trouble Code (DTC)	Is DTC B1637 displayed-	Diagnostic Chart with Trouble Code > DTC B1637 CURTAIN AIRBAG SENSOR LH LOST COMMUNICATION	Replace the side airbag sensor LH. Side Airbag Sensor > REMOVAL
8.CHECK AIRBAG CONTROL MODULE. 1) Turn the ignition switch to OFF, disconnect the battery ground cable, and wait for 60 seconds or more. 2) Restore the side airbag sensors RH and LH back to their original position. Side Airbag Sensor > REMOVAL 3) Connect all connectors. 4) Clear the memory. Clear Memory Mode 5) Perform the Inspection Mode. Inspection Mode 6) Read the DTC. (Current malfunction) Read Diagnostic Trouble Code (DTC)	Is DTC B1637 displayed-	Replace the airbag control module. Airbag Control Module > REMOVAL	Diagnostic Chart with Trouble Code > DTC B1637 CURTAIN AIRBAG SENSOR LH LOST COMMUNICATION
9.CHECK FOR ANY OTHER DTC ON DISPLAY. Read the DTC. (Current malfunction) Read Diagnostic Trouble Code (DTC)	Is any other DTC displayed-	Check DTC using “List of Diagnostic Trouble Code (DTC)”. List of Diagnostic Trouble Code (DTC)	Finish the diagnosis.

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