SRS -Troubleshooting52B-10
Code no.Page Diagnostic item
34*2Connector lock system52B-29
35SRS-ECU (deployed air bag) system52B-29
41*2Power supply circuit system (fuse No.2 circuit)52B-30
42*2Power supply circuit system (fuse No.3 circuit)52B-32
43*2SRS warning lamp drive circuit systemLamp does not illumi-
nate.52B-33
SRS warning lamp drive circuit systemLamp does not go out.52B-33
44*2SRS warning lamp drive circuit system52B-33
45SRS-EUC internal circuit system including non - volatile memory (EEPROM)52B-11
51Driver’s air bag module (squib) ignition drive circuit systemShort in the ignition
drive circuit52B-11
52Driver’s air bag module (squib) ignition drive circuit systemOpen in the ignition
drive circuit
54Front passenger’s air bag (squib) ignition drive circuit
systemShort in the ignition
drive circuit52B-11
55Front passenger’s air bag (squib) ignition drive circuit
systemOpen in the ignition
drive circuit
56Driver’s seat belt pre-tensioner (squib) ignition drive circuit
systemShort in the ignition
drive circuit52B-11
57Driver’s seat belt pre-tensioner (squib) ignition drive circuit
systemOpen in the ignition
drive circuit
58Front passenger’s seat belt pre-tensioner (squib) ignition
drive circuit systemShort in the ignition
drive circuit52B-11
59Front passenger’s seat belt pre-tensioner (squib) ignition
drive circuit systemOpen in the ignition
drive circuit
61Driver’s air bag module (squib) systemShort-circuited to
power supply52B-34
62Driver’s air bag module (squib) systemShort-circuited to earth
64Front passenger’s air bag module (squib) systemShort-circuited to
power supply52B-38
65Front passenger’s air bag module (squib) systemShort-circuited to earth
66Driver’s seat belt pre-tensioner (squib) systemShort-circuited to
power supply52B-39
67Driver’s seat belt pre-tensioner (squib) systemShort-circuited to earth
68Front passenger’s seat belt pre-tensioner (squib) systemShort-circuited to
power supply52B-40
69Front passenger’s seat belt pre-tensioner (squib) systemShort-circuited to earth
NOTE
(1) *1: If the trouble(s) are removed, the SRS warning lamp go out with diagnosis code history stored.
(2) *2: If the trouble(s) are removed, the SRS warning lamp will go out with diagnosis code history automatically erased.
(3) When the battery has been discharged, diagnosis code No.41 or 42 is stored. Check the battery when either of
these is displayed.
SRS -Troubleshooting52B-12
Code No.21 Driver’s air bag module (squib) systemPossible Cause
This code is output when short circuit occurs between terminals of the
SRS-ECU driver’s air bag module (squib) circuit.
However, SRS warning lamp goes out when a normal operation is resumed
(diagnosis code is not cleared.)DConnector engagement faulty or short bar faulty*
DShort circuit in the clock spring
DShort circuit between terminals of the driver’s air
bag module (squib) circuit
DFaulty connector
DSRS-ECU inoperable
NOTE:
(1) *: The connector of the squib circuit contains a short bar (short-circuiting the positive (+) cable and
the negative ( - ) cable to avoid an erroneous deployment caused by static electricity when a connector
is not connected). Thus, when a connector is connected, the short bar may not be released due
to improper engagement of the connector or faulty connector as shown in the illustration below.
Disconnect the connector as shown in the illustration below, then reconnect it. Check that a diagnosis
code is output again after erasing the memory. If the diagnosis code is not output, the above-mentioned
code is output due to improper engagement of the connector.
C-204C-207
SRS-ECU
Clock spring
Driver’s air bag module C-21
(2) Two different types of driver’s air bag modules by model are featured. Thus, two types of air bag
module by model are described in the following flowchart.
RS: Steering wheel and air bag module separate type
RS-II: Steering wheel and air bag module incorporate type
SRS -Troubleshooting52B-16
Code No.22 Driver’s air bag module (squib) systemPossible Cause
This code is output when open circuit occurs in the SRS-ECU driver’s air bag
module (squib) circuit.
However, SRS warning lamp goes out when a normal operation is resumed
(diagnosis code is not cleared.)DOpen in the clock spring
DHalf open in the circuit due to improper neutral
positioning of the clock spring
DOpen in the driver’s air bag module (squib) circuit
DDriver’s air bag module (squib) connector falling
out
DConnector improper contact
DSRS-ECU inoperable
NOTE:
Two different types of driver’s air bag modules by model are featured. Thus, two types of air bag module
by model are described in the following flowchart.
RS: Steering wheel and air bag module separate type
RS-II: Steering wheel and air bag module incorporate type
SRS -Troubleshooting52B-20
Code No.24 Front passenger’s air bag module (squib)
systemPossible Cause
This code is output when short circuit occurs between terminals of the
SRS-ECU front passenger’s air bag (squib) circuit.
However, SRS warning lamp goes out when a normal operation is resumed
(diagnosis code is not cleared.)DConnector engagement faulty or short bar faulty*
DShort circuit between terminals of the front
passenger’s air bag (squib) circuit
DFaulty connector
DSRS-ECU inoperable
NOTE:
*: The connector of the squib circuit contains a short bar (short-circuiting the positive (+) cable and the
negative ( - ) cable to avoid an erroneous deployment caused by static electricity when a connector is
not connected). Thus, when a connector is connected, the short bar may not be released due to improper
engagement of the connector or faulty connector as shown in the illustration below. Disconnect the connector
as shown in the illustration below, then reconnect it. Check that a diagnosis code is output again after
erasing the memory. If the diagnosis code is not output, the above-mentioned code is output due to
improper engagement of the connector.
C-21
SRS-ECUC-109
Front passenger’s air bag module
SRS -Troubleshooting52B-22
Code No.25 Front passenger’s air bag module (squib)
systemPossible Cause
This code is output when open circuit occurs in the SRS-ECU front passenger’s
air bag (squib) circuit.
However, SRS warning lamp goes out when a normal operation is resumed
(diagnosis code is not cleared.)DOpen in the front passenger’s air bag module
(squib) circuit
DConnector improper contact
DSRS-ECU inoperable
NG
Measure at the SRS-ECU connector C-21 and front
passenger’s air bag module connector C-109 .
DDisconnect the SRS-ECU connector C-21 and the front
passenger’s air bag module connector C-109 , and
measure at the harness side.
DContinuity check between the following terminals
Connector C-21 Connector C-109
9–2
10 – 1
Caution
Do not directly insert a probe or other devices at the
front of the connector to avoid a possible decrease in
the contact pressure.
OK:Continuity (2Ωor less)
YESNO
Replace the front passenger’s seat air bag module (squib).
MUT-II self-diag code
DConnect the dummy resistor (MB991865) to the resistor harness
(MB991866).
DDisconnect the front passenger’s air bag module connector C-109
and insert the resistor harness (MB991866) behind the harness side
connector.
Caution
Do not directly insert a probe or other devices at the front of the
connector to avoid a possible decrease in the contact pressure.
DConnect the negative ( - ) terminal of the battery
DCheck the diagnosis code again after erasing the memory.
Is code No.25 output?
Replace the SRS-ECU.
Check the trouble
symptoms.
NG
Check the harness between the front passenger’s air bag
module and the SRS-ECU, and repair if necessary.
OKNG
Correct
Check connector:C-21, C-109
OK
Resistor harness
(MB991866) Dummy resistor
(MB991865)
resistance (3Ω)
Instrumental panel
wiring harness
Front passenger’s air bag
module connector
Connector C-21Connector C-109
SRS -Troubleshooting52B-23
Code No.26 Driver’s seat belt pre-tensioner (squib)
systemPossible Cause
This code is output when short circuit occurs between terminals of the
SRS-ECU driver’s seat belt pre-tensioner (squib) circuit.
However, SRS warning lamp goes out when a normal operation is resumed
(diagnosis code is not cleared.)DConnector engagement faulty or short bar faulty*
DShort circuit between terminals of the driver’s seat
belt pre-tensioner (squib) circuit
DFaulty connector
DSRS-ECU inoperable
NOTE:
*: The connector of the squib circuit contains a short bar (short-circuiting the positive (+) cable and the
negative ( - ) cable to avoid an erroneous deployment caused by static electricity when a connector is
not connected). Thus, when a connector is connected, the short bar may not be released due to improper
engagement of the connector or faulty connector as shown in the illustration below. Disconnect the connector
as shown in the illustration below, then reconnect it. Check that a diagnosis code is output again after
erasing the memory. If the diagnosis code is not output, the above-mentioned code is output due to
improper engagement of the connector.
C-41C-133*1,
C-112*2
SRS-ECU
Driver’s seat belt
pre-tensioner
NOTE
*1: L.H. drive vehicles
*2: R.H. drive vehicles
D-28*1,
D-26*2
SRS -Troubleshooting52B-25
Code No.27 Driver’s seat belt pre-tensioner (squib)
systemPossible Cause
This code is output when open circuit occurs in the SRS-ECU driver’s seat belt
pre-tensioner (squib) circuit.
However, SRS warning lamp goes out when a normal operation is resumed
(diagnosis code is not cleared.)DConnector improper contact
DOpen in the driver’s seat pre-tensioner (squib)
circuit
DSRS-ECU inoperable
MUT-II self-diag code
DConnect the dummy harness (MB991865) to the resistor harness
(MB991866).
DDisconnect the driver’s seat belt pre-tensioner connector D-28*
1and
D-26*2and insert the resistor harness (MB991866) behind the harness
side connector.
Caution
Do not directly insert a probe or other devices at the front of the
connector to avoid a possible decrease in the contact pressure.
DConnect the negative ( - ) terminal of the battery
DCheck the diagnosis code again after erasing the memory.
Is code No.27 output?
YESNO
Replace the driver’s seat belt pre-tensioner.
Replace the SRS-ECU.
Check the trouble
symptoms.
NG
Check the harness between the driver’s seat belt pre-tensioner
and the SRS-ECU, and repair if necessary. NG
OK
OKNG
Correct
Check connector:D-28*1,D-26*2, C-133*1, C-112*2, C-124 Driver’s seat belt
pre-tensioner connector
Measure at the SRS-ECU connector C-41, the driver’s seat
belt pre-tensioner connector D-28*
1and D-26*2.
DDisconnect the SRS-ECU connector C-41 , the driver’s
seat belt pre-tensioner connector D-28*1and D-26*2, and
then measure at the harness side.
DContinuity check between the following terminals
Connector C-41 D-28*
1,D-26*2
29 – 2
30 – 1
Caution
Do not directly insert a probe or other devices at the
front of the connector to avoid a possible decrease in
the contact pressure.
OK:Continuity (2Ωor less)Resistor harness
(MB991866) Dummy resistor
(MB991865)
resistance (3Ω)
Instrumental panel
wiring harness
Connector C-41D-28*
1,D-26*2connector
NOTE
*1: L.H. drive vehicles
*2: R.H. drive vehicles
SRS -Troubleshooting52B-26
Code No.28 Front passenger’s seat belt pre-tensioner
(squib) systemPossible Cause
This code is output when short circuit occurs between terminals of the
SRS-ECU front passenger’s seat belt pre-tensioner (squib) circuit.
However, SRS warning lamp goes out when a normal operation is resumed
(diagnosis code is not cleared.)DConnector engagement faulty or short bar faulty*
DShort circuit between terminals of the front
passenger’s seat belt pre-tensioner (squib) circuit
DFaulty connector
DSRS-ECU inoperable
NOTE
*: The connector of the squib circuit contains a short bar (short-circuiting the positive (+) cable and the
negative ( - ) cable to avoid an erroneous deployment caused by static electricity when a connector is
not connected). Thus, when a connector is connected, the short bar may not be released due to improper
engagement of the connector or faulty connector as shown in the illustration below. Disconnect the connector
as shown in the illustration below, then reconnect it. Check that a diagnosis code is output again after
erasing the memory. If the diagnosis code is not output, the above-mentioned code is output due to
improper engagement of the connector.
C-41C-133*1,
C-112*2D-28*1,
D-26*2
SRS-ECUFront passenger’s seat
belt pre-tensioner
NOTE
*1: L.H. drive vehicles
*2: R.H. drive vehicles