Mitsubishi Colt Ralliart. Manual — part 571
TROUBLESHOOTING
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-122
DIAGNOSIS PROCEDURE
STEP 1. Check the diagnosis code by connecting
a dummy resistor. (M.U.T.-III diagnosis code)
(1) Disconnect the negative battery terminal.
(2) Disconnect the side-airbag module (LH)
connector C-23.
(3) Connect special tool dummy resistor (MB991865)
to special tool resistor harness (MB991866).
CAUTION
Do not insert a test probe into the terminal from
its front side directly as the connector contact
pressure may be weakened.
(4) Insert special tool (MB991866) into the C-23
harness side connector by backprobing.
(5) Connect the negative battery terminal.
(6) Erase the diagnosis code memory, and check the
diagnosis code.
Q: Is diagnosis code 85 set?
YES :
Go to Step 2.
NO :
Replace the frame assembly of the front
seat (LH) (Refer to GROUP 52A, Front Seat
).
STEP 2. Voltage measurement at the SRS-ECU
connector B-34
(1) Disconnect SRS-ECU connector B-34.
DANGER
To prevents the air bag from deploying unin-
tentionally, disconnect the side-airbag mod-
ule (LH) connector C-23 to short the squib
circuit.
(2) Disconnect left hand side-airbag module (LH)
connector C-23.
(3) Connect the negative battery terminal.
(4) Turn the ignition switch to the "ON" position.
CAUTION
Do not insert a test probe into the terminal from
its front side directly as the connector contact
pressure may be weakened.
(5) Voltage measurement between B-34 harness
side connector terminals 21, 22 and body earth.
OK: 0 V
AC401575
Connector: C-23
AC
C-23 (R)
2 1
Harness side
connector
(front view)
AC006042 CM
MB991866
(Resistor harness)
C-23
Intermediate h
arness side
connector
MB991865 (Dummy
resistor: 3
Ω)
C-23 Side-airbag
module (LH) connector
AC206285
AG
B-34 (Y)
Connector: B-34
Harness side
connector
(rear view)
343536373839404142
252627282930313233
2122
2324
AC401575
Connector: C-23
AC
C-23 (R)
2 1
Harness side
connector
(front view)
34 35 36 37 38 39 40 41 42
25 26 27 28 29 30 31 32 33
21 22
23 24
AC208820
B-34 Harness side
connector (rear view)
AE
Main
Index
Group
TOC
TROUBLESHOOTING
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-123
Q: Is the check result normal?
YES :
Go to Step 3.
NO :
Repair the harness wires between
SRS-ECU connector B-34 (terminal No.21
and 22) and side-airbag module (LH)
connector C-23 (terminal No.1 and 2).
STEP 3. Check whether the diagnosis code is
reset.
Q: Is diagnosis code 85 set?
YES :
Replace the SRS-ECU (Refer to
).
NO :
An intermittent malfunction is suspected
(Refer to GROUP 00, How to Cope with
Intermittent Malfunction
).
Code No.86: Side-airbag module (squib) (LH) system (short-circuited to the earth)
OPERATION
• The SRS-ECU judges how severe a collision is
by detecting signals from the left and right side
impact sensors. If the impact is over a predeter-
mined level, the SRS-ECU sends an ignition sig-
nal. At this time, if the side-airbag safing
G-sensor is on, the SRS side-airbag will inflate.
• The ignition signal is input to the side-airbag
module to inflate the side-airbag.
DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set if the side-airbag squib
(LH) wire(s) are short-circuited to the earth.
PROBABLE CAUSES
• Damaged wiring harnesses or connectors
• Short to earth in the left hand side-airbag module
(squib) harness
• Malfunction of the SRS-ECU
AC510246
AIR BAG DRIVE
CIRCUIT
MICRO COMPUTER
SRS-ECU
SIDE-AIRBAG
MODULE
(SQUIB)
(LH)
Wire colour code
B : Black LG : Light green
G : Green L : Blue
W : White Y : Yellow
SB : Sky blue BR : Brown
O : Orange GR : Grey
R : Red P : Pink V : Violet
NOTE
CONNECTOR
COUPLED: ON
CONNECTOR
UNCOUPLED: OFF
CONNECTOR
LOCK
SWITCH
CONNECTOR
LOCK
SWITCH
Side-airbag Module (LH) (Squib) Circuit
AB
Main
Index
Group
TOC
TROUBLESHOOTING
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-124
DIAGNOSIS PROCEDURE
STEP 1. Check the diagnosis code by connecting
a dummy resistor. (M.U.T.-III diagnosis code)
(1) Disconnect the negative battery terminal.
(2) Disconnect the side-airbag module (LH)
connector C-23.
(3) Connect special tool dummy resistor (MB991865)
to special tool resistor harness (MB991866).
CAUTION
Do not insert a test probe into the terminal from
its front side directly as the connector contact
pressure may be weakened.
(4) Insert special tool (MB991866) into the C-23
harness side connector by backprobing.
(5) Connect the negative battery terminal.
(6) Erase the diagnosis code memory, and check the
diagnosis code.
Q: Is diagnosis code 86 set?
YES :
Go to Step 2.
NO :
Replace the frame assembly of the front
seat (LH) (Refer to GROUP 52A, Front Seat
).
STEP 2. Resistance measurement at the
SRS-ECU connector B-34
(1) Disconnect SRS-ECU connector B-34.
(2) Disconnect side-airbag module (LH) connector
C-23.
CAUTION
Do not insert a test probe into the terminal from
its front side directly as the connector contact
pressure may be weakened.
(3) Check for continuity between B-34 harness side
connector terminals 21, 22 and body earth.
OK: Open circuit
Q: Is the check result normal?
YES :
Go to Step 3.
NO :
Repair the harness wires between
SRS-ECU connector B-34 (terminal No.21
and 22) and side-airbag module (LH)
connector C-23 (terminal No.1 and 2).
AC401575
Connector: C-23
AC
C-23 (R)
2 1
Harness side
connector
(front view)
AC006042 CM
MB991866
(Resistor harness)
C-23
Intermediate h
arness side
connector
MB991865 (Dummy
resistor: 3
Ω)
C-23 Side-airbag
module (LH) connector
AC206285
AG
B-34 (Y)
Connector: B-34
Harness side
connector
(rear view)
343536373839404142
252627282930313233
2122
2324
AC401575
Connector: C-23
AC
C-23 (R)
2 1
Harness side
connector
(front view)
34 35 36 37 38 39 40 41 42
25 26 27 28 29 30 31 32 33
21 22
23 24
AC100392
B-34 Harness side
connector (rear view)
AR
Main
Index
Group
TOC
TROUBLESHOOTING
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-125
STEP 3. Check whether the diagnosis code is
reset.
Q: Is diagnosis code 86 set?
YES :
Replace the SRS-ECU (Refer to
).
NO :
An intermittent malfunction is suspected
(Refer to GROUP 00, How to Cope with
Intermittent Malfunction
).
Code No.89: Side impact sensor (RH) communication error
Code No.96: Side impact sensor (RH) communication impossible
OPERATION
The side impact sensor includes an analogue G-sen-
sor and CPU, etc. The CPU monitors the analogue
G-sensor output signal. If the CPU judges that the
side-airbags should be deployed, it sends a fire sig-
nal to the SRS-ECU to deploy the side-airbags.
Besides that, the CPU diagnoses the internal compo-
nents of the side impact sensor. If a malfunction
occurs, it requests the SRS-ECU to set a diagnosis
code.
DIAGNOSIS CODE SET CONDITIONS
These diagnosis codes are set if communication
between the side impact sensor (RH) and the
SRS-ECU is not possible or faulty.
PROBABLE CAUSES
• Damaged wiring harnesses or connectors
• Malfunction of the side impact sensor (RH)
• Malfunction of the SRS-ECU
AC510252
MICRO COMPUTER
INTERFACE
CIRCUIT
CPU
SRS-ECU
ANALOGUE
G SENSOR
EEP ROM
SIDE IMPACT
SENSOR (RH)
CONSTANT
VOLTAGE CIRCUIT
Wire colour code
B : Black LG : Light green G : Green L : Blue W : White Y : Yellow SB : Sky blue
BR : Brown O : Orange GR : Grey R : Red P : Pink V : Violet
Side Impact Sensor (RH) Circuit
AB
Main
Index
Group
TOC
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