Lexus RX300 (MCU15). Service manual - part 291

H01018

AB0118 AB0119

H01084

H10600

H10632

→ ←

ON

Airbag
Sensor
Assembly

P/T  Squib (LH)

DTC B0137/71

DLC3

Tc

CG

DI–396

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

LEXUS RX300   (RM785E)

4

Check P/T squib (LH).

PREPARATION:
(a)

Turn the ignition switch to LOCK.

(b)

Disconnect negative (–) terminal cable from the battery,
and wait at least for 90 seconds.

(c)

Connect the seat belt pretensioner (LH) connector.

(d)

Connect negative (–) terminal cable to the battery, and
wait at least for 2 seconds.

CHECK:
(a)

Turn the ignition switch to ON, and wait at least for 20 se-
conds.

(b)

Clear the DTC stored in memory (See step 5 on page 
DI–305).

(c)

Turn the ignition switch to LOCK, and wait at least for 20
seconds.

(d)

Turn the ignition switch to ON, and wait at least for 20 se-
conds.

(e)

Check the DTC (See page DI–305).

OK:

DTC B0137/71 is not output.

HINT:
Codes other than code B0137/71 may be output at this time, but
they are not relevant to this check.

NG 

Replace seat belt pretensioner (LH).

OK

From the results of the above inspection, the malfunctioning part can now be considered normal.
To make sure of this, use the simulation method to check. If the malfunctioning part can not be
detected by the simulation method, replace all SRS components including the wire harness.

H16272

H01016

AB0119

H16791

Airbag 
Sensor 
Assembly

P/T Squib (LH)

PL+

(–)

(+)

ON

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

DI–397

LEXUS RX300   (RM785E)

DTC

B0138/72

Short in P/T Squib (LH) Circuit (to B+)

CIRCUIT DESCRIPTION

The P/T squib (LH) circuit consists of the airbag sensor assembly and seat belt pretensioner (LH). 
It causes the SRS to deploy when the SRS deployment conditions are satisfied. 
For details of the function of each component, see OPERATION on page RS–2. 
DTC B0138/72 is recorded when a B+ short is detected in the P/T squib (LH) circuit.

DTC No.

DTC Detecting Condition

Trouble Area

B0138/72

S Short circuit in seat belt pretensioner (LH) wire harness 

(to B+)

S P/T squib (LH) malfunction

S Airbag sensor assembly malfunction

S Seat belt pretensioner (LH)

S Airbag sensor assembly

S Wire harness

WIRING DIAGRAM

See page DI–387.

INSPECTION PROCEDURE

1

Prepare for inspection (See step 1 on page DI–431).

2

Check P/T squib (LH) circuit.

CHECK:
(a)

Turn the ignition switch to ON.

(b)

For the connector (on the seat belt pretensioner side) be-
tween the seat belt pretensioner (LH) and the airbag sen-
sor assembly, measure the voltage between PL+ and
body ground.

OK:

Voltage: 0 V

NG

Repair or replace harness or connector be-
tween seat belt pretensioner (LH) and airbag
sensor assembly.

OK

DI6PQ–06

H16273

H01017

AB0119
H01085

H10600

H16792

P/T Squib (LH)

Airbag
Sensor
Assembly

PL+

PL–

DTC B0138/72

ON

→

 ←

DLC3

Tc

CG

DI–398

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

LEXUS RX300   (RM785E)

3

Check airbag sensor assembly.

PREPARATION:
(a)

Connect the connector to the airbag sensor assembly.

(b)

Using a service wire, connect PL+ and PL– of the connec-
tor (on the seat belt pretensioner side) between the seat
belt pretensioner (LH) and the airbag sensor assembly.

(c)

Connect negative (–) terminal cable to the battery, and
wait at least for 2 seconds.

CHECK:
(a)

Turn the ignition switch to ON and wait at least for 20 se-
conds.

(b)

Clear the DTC stored in memory (See step 5 on page 
DI–305).

(c)

Turn the ignition switch to LOCK, and wait at least for 20
seconds.

(d)

Turn the ignition switch to ON, and wait at least for 20 se-
conds.

(e)

Check the DTC (See page DI–305).

OK:

DTC B0138/72 is not output.

HINT:
Codes other than code B0138/72 may be output at this time, but
they are not relevant to this check.

NG

Replace airbag sensor assembly.

OK

AB0119

H01018

H01085

H10600

H10634

→ ←

ON

Airbag
Sensor
Assembly

P/T Squib (LH)

DTC B0138/72

DLC3

Tc

CG

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

DI–399

LEXUS RX300   (RM785E)

4

Check P/T squib (LH).

PREPARATION:
(a)

Turn the ignition switch to LOCK.

(b)

Disconnect negative (–) terminal cable from the battery,
and wait at least for 90 seconds.

(c)

Connect the seat belt pretensioner (LH) connector.

(d)

Connect negative (–) terminal cable to the battery, and
wait at least for 2 seconds.

CHECK:
(a)

Turn the ignition switch to ON, and wait at least for 20 se-
conds.

(b)

Clear the DTC stored in memory (See step 5 on page 
DI–305).

(c)

Turn the ignition switch to LOCK, and wait at least for 20
seconds.

(d)

Turn the ignition switch to ON, and wait at least for 20 se-
conds.

(e)

Check the DTC (See page DI–305).

OK:

DTC B0138/72 is not output.

HINT:
Codes other than code B0138/72 may be output at this time, but
they are not relevant to this check.

NG 

Replace seat belt pretensioner (LH).

OK

From the results of the above inspection, the malfunctioning part can now be considered normal.
To make sure of this, use the simulation method to check. If the malfunctioning part can not be
detected by the simulation method, replace all SRS components including the wire harness.