DTC B1637: Curtain Shield Airbag Sensor Lost Communication (LH); DTC B1638: Curtain Shield Airbag Sensor Initialization Error (LH) [04/2018 -]: Description

WARNING: This page is about a different car, the 2022 Toyota Avalon, 2021 Toyota Avalon, 2020 Toyota Avalon, and 2019 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.

The side collision sensor LH circuit (bus 1) consists of the airbag ECU assembly, side airbag pressure sensor LH and side No. 2 airbag sensor LH.

The side airbag pressure sensor LH and side No. 2 airbag sensor LH detect impacts to the vehicle and send signals to the airbag ECU assembly to determine if the airbags and pretensioners should be deployed.

These DTCs are stored when a malfunction is detected in the side collision sensor LH circuit (bus 1).

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Warning Indicate	Test Mode / Check Mode
B1637	Curtain Shield Airbag Sensor Lost Communication (LH)	The airbag ECU assembly detects a line short, short to ground or B+, or an open in the side collision sensor LH circuit (bus 1). Side airbag pressure sensor LH malfunction Side No. 2 airbag sensor LH malfunction Airbag ECU assembly malfunction	Floor wire Front door wire LH Side airbag pressure sensor LH Side No. 2 airbag sensor LH Airbag ECU assembly	Comes on	Does not apply to test/check mode
B1638	Curtain Shield Airbag Sensor Initialization Error (LH)	The airbag ECU assembly detects a line short, short to ground or B+, or an open in the side collision sensor LH circuit (bus 1). Side airbag pressure sensor LH malfunction Side No. 2 airbag sensor LH malfunction Airbag ECU assembly malfunction	Floor wire Front door wire LH Side airbag pressure sensor LH Side No. 2 airbag sensor LH Airbag ECU assembly	Comes on	Does not apply to test/check mode