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
SRS -Troubleshooting52B-27
YESNO
Replace the front passenger’s seat belt pre-tensioner.
MUT-II self-diag code
DConnect the dummy harness (MB991865) to the resistor harness
(MB991866).
DDisconnect the front passenger’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.28 output?
Replace the SRS-ECU.
Check the trouble
symptoms.
NG
Check the harness between the front passenger’s seat belt
pre-tensioner and the SRS-ECU, and repair if necessary. NG
Figure A
Short bar
Front view of SRS-ECU
connector C-41
(harness side)
OKNG
Correct
Check connector:D-28*1, D-26*2, C-133*1, C-112*2, C-41
Measure at the SRS-ECU connector C-41.
DDisconnect the SRS-ECU connector C-41.
DDisconnect the front passenger’s seat belt pre-tensioner
connector D-28
*1and D-26*2
.
Caution
Disconnect the connector and short-circuit the squib
circuit before releasing the short bar of the SRS-ECU
connector in the following operation.
DCable bands between terminals 27, 28 and the short bar
(width:3 mm, thickness:0.5 mm) between terminals 11 and
12 and the short bar, and release the short bar.
(See Figure A.)
Caution
As the short bar may not be releasable if inserted
insufficiently, insert more than 4 mm.
DMeasure at the harness side
DContinuity check between terminals 27 and 28
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:No continuityTerminal
Cable
band and etc.
Section
A-A
A
A
4 mm or more Resistor harness
(MB991866) Dummy resistor
(MB991865)
resistance (3Ω)
Instrumental panel
wiring harness
Front passenger’s seat belt
pre-tensioner connectorConnector C-41
OK
NOTE
*1: L.H. drive vehicles
*2: R.H. drive vehicles
SRS -Troubleshooting52B-28
Code No.29 Front passenger’s seat belt pre-tensioner
(squib) systemPossible Cause
This code is output when open circuit occurs in 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.)DOpen in the front passenger’s seat pre-tensioner
(squib) circuit
DConnector improper contact
DSRS-ECU inoperable
Measure at the SRS-ECU connector C-41 , the front
passenger’s seat belt pre-tensioner connector D-28*
1and
D-26*2.
DDisconnect the SRS-ECU connector C-41 , the front
passenger’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, Connector D-26*2
28 – 2
27 – 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 belt pre-tensioner.
MUT-II self-diag code
DConnect the dummy harness (MB991865) to the resistor harness
(MB991866).
DDisconnect the front passenger’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.29 output?
Replace the SRS-ECU.
Check the trouble
symptoms.
NG
Check the harness between the front passenger’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-41 Resistor harness
(MB991866) Dummy resistor
(MB991865)
resistance (3Ω)
Instrumental panel
wiring harness
Front passenger’s seat belt
pre-tensioner connector
Connector C-41Connector D-28*
1, D-26*2
NOTE
*1: L.H. drive vehicles
*2: R.H. drive vehicles
SRS -Troubleshooting52B-38
Code No.64 Front passenger’s air bag module (squib)
system (short-circuited to power supply)Possible Cause
Code No.65 Front passenger’s air bag module (squib)
system (short-circuited to earth)
This code is output when the input terminal of the SRS-ECU front passenger’s
air bag module (squib) is short-circuited to power supply (code No.64) or
short-circuited to earth (code No.65).DHarness or connector fault
DThe harness of the front passenger’s air bag
module (squib) is short-circuited to power supply
(code No.64) or short-circuited to earth (code
No.65).
DSRS-ECU inoperable
Measure at the SRS-ECU connector C-21.
DDisconnect the SRS-ECU connector C-21.
DDisconnect the front passenger’s air bag
module connector C-109 .
DMeasure at the harness side
DContinuity between terminal 9 or 10 and body
earth
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:No continuity
NO
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.64 or No.65 output?
YES (when No.65 is output)YES (when No.64 is output)
Replace the SRS-ECU.
Measure at the SRS-ECU connector C-21.
DDisconnect the SRS-ECU connector C-21.
DDisconnect the front passenger’s air bag
module connector C-109 .
DIgnition switch:ON
DMeasure at the harness side
DVoltage between terminal 9 or 10 and body
earth
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:0V
NG
Replace the SRS-ECU.
Correct
Check connector:C-21, C-109
Check the trouble symptoms.
Check the harness between the front
passenger’s air bag module and the
SRS-ECU, and repair if necessary.OK
NG
OK
NG
OK
NG
Resistor harness
(MB991866) Dummy resistor
(MB991865)
resistance (3Ω)
Instrumental panel
wiring harness
Front passenger’s air bag
module connector
Connector C-21Connector C-21
SRS -Troubleshooting52B-39
Code No.66 Driver’s seat belt pre-tensioner (squib)
system (short-circuited to power supply)Possible Cause
Code No.67 Driver’s seat belt pre-tensioner (squib)
system (short-circuited to earth)
This code is output when the input terminal of the SRS-ECU driver’s seat belt
pre-tensioner (squib) is short-circuited to power supply (code No.66) or
short-circuited to earth (code No.67).DHarness or connector fault
DThe harness of the driver’s seat belt pre-tensioner
(squib) is short-circuited to power supply (code
No.66) or short-circuited to earth (code No.67).
DSRS-ECU inoperable
Replace the SRS-ECU. OK
Measure at the SRS-ECU connector C-41 .
DDisconnect the SRS-ECU connector C-41.
DDisconnect the driver’s seat belt pre-tensioner
D-28*
1and D-26*2.
DMeasure at the harness side
DContinuity between terminal 29 or 30 and
body earth
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:No continuity
NO
Replace the driver’s seat belt pre-tensioner.
MUT-II self-diag code
DConnect the dummy resistor (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.66 or No.67 output?
YES (when No.67 is output)YES (when No.66 is output)
Replace the SRS-ECU.
Measure at the SRS-ECU connector C-41 .
DDisconnect the SRS-ECU connector C-41.
DDisconnect the driver’s seat belt pre-tensioner
D-28*
1and D-26*2.
DIgnition switch:ON
DMeasure at the harness side
DVoltage between terminal 29 or 30 and body
earth
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:0V
NG
Check connector:D-28*1, D-26*2, C-133*1, C-112*2, C-41
Check the trouble symptoms.
Check the harness between the driver’s seat belt pre-tensioner and the SRS-ECU,
and repair if necessary.
NG
OK
NG
OKResistor harness
(MB991866) Dummy resistor
(MB991865)
resistance (3Ω)
Instrumental panel
wiring harness
Driver’s seat belt
pre-tensioner connector
Connector C-41
Connector C-41
NOTE
*1: L.H. drive vehicles
*2: R.H. drive vehicles
SRS -Troubleshooting52B-40
Code No.68 Front passenger’s seat belt pre-tensioner
(squib) system (short-circuited to power supply)Possible Cause
Code No.69 Front passenger’s seat belt pre-tensioner
(squib) system (short-circuited to earth)
This code is output when the input terminal of the SRS-ECU front passenger’s
seat belt pre-tensioner (squib) is short-circuited to power supply (code No.68) or
short-circuited to earth (code No.69).DHarness or connector fault
DThe harness of the front passenger’s seat belt
pre-tensioner (squib) is short-circuited to power
supply (code No.68) or short-circuited to earth
(code No.69).
DSRS-ECU inoperable
NO
Replace the front passenger’s seat belt pre-tensioner.
MUT-II self-diag code
DConnect the dummy resistor (MB991865) to the resistor harness
(MB991866).
DDisconnect the front passenger’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.68 or No.69 output?
YES (when No.69 is output)YES (when No.68 is output)
Replace the SRS-ECU.
Measure at the SRS-ECU connector C-41 .
DDisconnect the SRS-ECU connector C-41.
DDisconnect the front passenger’s seat belt
pre-tensioner connector D-28*
1and D-26*2.
DIgnition switch:ON
DMeasure at the harness side
DVoltage between terminal 27 or 28 and body
earth
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:0V
NG
Replace the SRS-ECU.
Correct
Check connector:D-28*1, D-26*2, C-133*1, C-112*2, C-41
Check the trouble symptoms.
Check the harness between the front passenger’s seat belt pre-tensioner and the
SRS-ECU, and repair if necessary.OK
Measure at the SRS-ECU connector C-41 .
DDisconnect the SRS-ECU connector C-41.
DDisconnect the front passenger’s seat belt
pre-tensioner connector D-28*
1and D-26*2.
DMeasure at the harness side
DContinuity between terminal 27 or 28 and
body earth
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:No continuity
NG
OK
NG
OK
NG
Resistor harness
(MB991866) Dummy resistor
(MB991865)
resistance (3Ω)
Instrumental panel
wiring harness
Front passenger’s seat belt
pre-tensioner connector
Connector C-41 Connector C-41
NOTE
*1: L.H. drive vehicles
*2: R.H. drive vehicles