Mitsubishi Galant 9G. Manual — part 1426
SRS AIR BAG DIAGNOSIS
TSB Revision
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-114
STEP 3. Check the front impact sensor (LH) power supply
circuit. Measure the voltage at the front impact sensor (LH)
connector A-23.
(1) Disconnect the negative battery terminal.
(2) Disconnect front impact sensor (LH) connector A-23, and
measure at the wiring harness side.
(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) Measure the voltage between A-23 harness side connector
terminal 2 and ground.
Voltage should measure 9 volts or more
Q: Is the measured voltage within the specified range?
YES : Replace the front impact sensor (LH) (Refer to
NO : Go to Step 4.
STEP 4. Check the harness wires for open circuit or short
circuit between SRS-ECU connector C-121 (terminal No.38
and 39) and front impact sensor (LH) connector A-23
(terminal No.1 and 2).
AC305210
CONNECTOR: A-23
AT
A-23 (Y)
HARNESS SIDE
AC308161
A-23 HARNESS SIDE
CONNECTOR
(REAR VIEW)
AC
AC305362
CONNECTOR: C-121
C-121 (Y)
AH
SRS-ECU
C-121
HARNESS SIDE
CONNECTOR
(REAR VIEW)
42
31
38
27
21
41
28
39
22
30
25
47
36
33
44
34
45
37
48
26
29
23
40
32
43
35
46
24
B
A
AC305210
CONNECTOR: A-23
AT
A-23 (Y)
HARNESS SIDE
SRS AIR BAG DIAGNOSIS
TSB Revision
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-115
NOTE: After inspecting intermediate connectors C-22 and C-29
inspect the wiring harness. If the intermediate connectors C-22
and C-29 is damaged, repair or replace it.
Q: Are the harness wires between SRS-ECU connector
C-121 (terminal No.38 and 39) and front impact sensor
(LH) connector A-23 (terminal No.1 and 2) in good
condition?
YES : Erase the diagnostic trouble code memory, and check
the diagnostic trouble code. If DTC B1417 sets,
replace the SRS-ECU (Refer to
). Then go
to Step 5.
NO : Replace the harness wires between SRS-ECU
connector C-121 and front impact sensor (LH)
connector A-23. Then go to Step 5.
STEP 5. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC B1417 set?
YES : Return to Step 1.
NO : The procedure is complete.
AC305233 AI
CONNECTOR: C-22
C-22 (Y)
AC305231AI
CONNECTOR: C-29
AC305412
AB
MB991910
DATA LINK
CONNECTOR
MB991824
MB991827
SRS AIR BAG DIAGNOSIS
TSB Revision
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-116
DTC B1418: Front Impact Sensor (LH) (Squib) for Power Supply Circuit
DTC B1419: Front Impact Sensor (LH) (Squib) for Communication System
CAUTION
If DTC B1418 or B1419 is set in the SRS-ECU,
always diagnose the CAN main bus line.
.
Front Impact Sensor Circuit
INTERFACE CIRCUIT
SRS-ECU
FRONT IMPACT
SENSOR (LH)
FRONT IMPACT
SENSOR (RH)
AC305210
CONNECTOR: A-23
AW
A-23 (Y)
AC305233 AO
CONNECTOR: C-22
C-22 (Y)
AC305231BF
CONNECTOR: C-29
AC305362
CONNECTOR: C-121
C-121 (Y)
AD
SRS-ECU
SRS AIR BAG DIAGNOSIS
TSB Revision
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-117
CIRCUIT OPERATION
The front impact sensor includes an analog G sensor
and CPU, etc. The CPU monitors the analog G sen-
sor output signal. If the CPU judges that the front air
bags should be deployed, it sends a fire signal to the
SRS-ECU to deploy the front air bags. In addition,
the CPU diagnoses the internal components of the
front impact sensor. If a malfunction occurs, it
requests the SRS-ECU to set a diagnostic trouble
code.
.
DTC SET CONDITIONS
These DTCs are set if communication between the
front impact sensor (LH) and the SRS-ECU is not
possible or faulty.
.
TROUBLESHOOTING HINTS
• Damaged wiring harnesses or connectors
• Malfunction of the front impact sensor (LH)
• Malfunction of the SRS-ECU
.
DIAGNOSIS
Required Special Tool:
• MB991958: Scan Tool (MUT-III Sub Assembly)
• MB991824: Vehicle Communication Interface (V.C.I.)
• MB991827: MUT-III USB Cable
• MB991910: MUT-III Main Harness A (Vehicles with CAN
communication system)
• MB991223 (MB991222): Harness set (Probe)
STEP 1. Using scan tool MB991958, diagnose the CAN bus
line.
CAUTION
To prevent damage to scan tool MB991958, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958. Refer to "How to connect the
scan tool
."
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the CAN bus line found to be normal?
YES : Go to Step 2.
NO : Repair the CAN bus line (Refer to GROUP 54C,
AC305412
AB
MB991910
DATA LINK
CONNECTOR
MB991824
MB991827
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