Mitsubishi Galant 9G. Manual — part 1417
SRS AIR BAG DIAGNOSIS
TSB Revision
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-78
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 (RH) and the SRS-ECU is not
possible or faulty.
.
TROUBLESHOOTING HINTS
• Damaged wiring harnesses or connectors
• Malfunction of the front impact sensor (RH)
• 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)
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
SRS AIR BAG DIAGNOSIS
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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-79
STEP 2. 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 the DTC set?
YES : Go to Step 3.
NO : There is an intermittent malfunction such as poor
engaged connector(s) or open circuit (Refer to
GROUP 00, How to Use Troubleshooting/Inspection
Service Points
− How to Cope with Intermittent
Malfunctions ).
STEP 3. Check for any diagnostic trouble code. (Using
scan tool MB991958, read the diagnostic trouble code.)
Check the front impact sensor (RH).
(1) Disconnect the negative battery terminal.
(2) Replace the front impact sensor (RH) with the front impact
sensor (LH).
(3) Connect the negative battery terminal.
(4) Erase diagnostic trouble code from memory, and check the
diagnostic trouble code.
Q: Is DTC B1418 or B1419 set?
YES : Replace the front impact sensor (RH) with a new one
(Refer to
NO : Go to Step 4.
AC305412
AB
MB991910
DATA LINK
CONNECTOR
MB991824
MB991827
AC305412
AB
MB991910
DATA LINK
CONNECTOR
MB991824
MB991827
SRS AIR BAG DIAGNOSIS
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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-80
STEP 4. Check the harness wires for open circuit or short
circuit between SRS-ECU connector C-121 (terminal No.47
and 48) and front impact sensor (RH) connector A-27
(terminal No.1 and 2).
NOTE: After inspecting intermediate connectors C-22 and C-11
inspect the wiring harness. If the intermediate connectors C-22
and C-11 are damaged, repair or replace it.
Q: Are the harness wires between SRS-ECU connector
C-121 (terminal No.47 and 48) and front impact sensor
(RH) connector A-27 (terminal No.1 and 2) in good
condition?
YES : Erase the diagnostic trouble code memory, and check
the diagnostic trouble code. If DTC B1408 or B1409
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 (RH)
connector A-27. Then go to Step 5.
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
AC305206
A-27 (Y)
HARNESS SIDE
BA
CONNECTOR: A-27
AC305233 AI
CONNECTOR: C-22
C-22 (Y)
AC305233CN
CONNECTOR: C-11
SRS AIR BAG DIAGNOSIS
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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-81
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 B1408 or B1409 set?
YES : Return to Step 1.
NO : The procedure is complete.
AC305412
AB
MB991910
DATA LINK
CONNECTOR
MB991824
MB991827
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