Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Front Airbag Sensor Lost Communication (LH) (B1617,B1618)

DESCRIPTION

The front airbag sensor LH circuit consists of the airbag ECU assembly and front airbag sensor LH.

The front airbag sensor LH detects impacts to the vehicle and sends 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 front airbag sensor LH circuit.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

After turning the engine switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) battery terminal notices before proceeding with work.

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PROCEDURE

(a) Turn the engine switch off.

(b) Disconnect the cable from the negative (-) battery terminal.

CAUTION:

Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

(c) Check that the connectors are properly connected to the airbag ECU assembly and front airbag sensor LH. Also check that the connectors that link the engine room main wire and instrument panel wire are properly connected.

OK:

The connectors are properly connected.

NG

CONNECT CONNECTORS PROPERLY

OK

(a) Disconnect the connectors from the airbag ECU assembly and front airbag sensor LH. Also disconnect the connectors that link the engine room main wire and instrument panel wire.

(b) Check that the terminals of the connectors are not deformed or damaged.

OK:

The terminals are not deformed or damaged.

NG

REPLACE INSTRUMENT PANEL WIRE OR ENGINE ROOM MAIN WIRE

OK

(a) Connect the connectors that link the engine room main wire and instrument panel wire.

*1 Front Airbag Sensor LH *2 Airbag ECU Assembly *3 Engine Room Main Wire *4 Instrument Panel Wire *5 Service Wire *a Front view of wire harness connector (to Airbag ECU Assembly) *b Front view of wire harness connector (to Front Airbag Sensor LH)

(b) Connect the cable to the negative (-) battery terminal.

(c) Turn the engine switch on (IG).

(d) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

(e) Turn the engine switch off.

(f) Disconnect the cable from the negative (-) battery terminal.

CAUTION:

Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

(g) Using a service wire, connect terminals 30 (+SL) and 31 (-SL) of connector B.

NOTICE:

Do not forcibly insert the service wire into the terminals of the connector when connecting the wire.

(h) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

(i) Disconnect the service wire from connector B.

(j) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

NG

GO TO STEP 5

OK

(a) Connect the connector to the airbag ECU assembly.

*1 Front Airbag Sensor RH *2 Airbag ECU Assembly

(b) Interchange the front airbag sensor LH with RH and connect the connectors.

(c) Connect the cable to the negative (-) battery terminal.

(d) Turn the engine switch on (IG), and wait for at least 60 seconds.

(e) Clear the DTCs stored in memory.

(f) Turn the engine switch off.

(g) Turn the engine switch on (IG), and wait for at least 60 seconds.

(h) Check for DTCs.

HINT:

Codes other than DTCs B1612, B1613, B1617 and B1618 may be output at this time, but they are not related to this check.

(i) Turn the engine switch off.

(j) Disconnect the cable from the negative (-) battery terminal.

CAUTION:

Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

(k) Return the front airbag sensor LH and RH to their original positions and connect the connectors.

A

USE SIMULATION METHOD TO CHECK

B

REPLACE AIRBAG ECU ASSEMBLY

C

REPLACE FRONT AIRBAG SENSOR LH

(a) Disconnect the instrument panel wire connector from the engine room main wire.

*1 Front Airbag Sensor LH *2 Airbag ECU Assembly *3 Engine Room Main Wire *4 Instrument Panel Wire *5 Service Wire *a Front view of wire harness connector (to Airbag ECU Assembly) *b Front view of wire harness connector (to Engine Room Main Wire)

(b) Connect the cable to the negative (-) battery terminal.

(c) Turn the engine switch on (IG).

(d) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

(e) Turn the engine switch off.

(f) Disconnect the cable from the negative (-) battery terminal.

CAUTION:

Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

(g) Using a service wire, connect terminals 30 (+SL) and 31 (-SL) of connector B.

NOTICE:

Do not forcibly insert the service wire into the terminals of the connector when connecting the wire.

(h) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

(i) Disconnect the service wire from connector B.

(j) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

OK

REPLACE ENGINE ROOM MAIN WIRE

NG

REPLACE INSTRUMENT PANEL WIRE