Mitsubishi 380. Manual — part 791
SRS AIR BAG DIAGNOSIS
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-88
STEP 3. Check for any diagnostic trouble code. (Using
diagnostic tool MB991958, read the diagnostic trouble
code.)
Check the front impact sensor (LH).
(1) Disconnect the negative battery terminal.
(2) Replace the front impact sensor (LH) with the front impact
sensor (RH).
(3) Connect the negative battery terminal.
(4) Erase diagnostic trouble code from memory, and check the
diagnostic trouble code.
Q: Is DTC B1408 or B1409 set?
YES : Replace the front impact sensor (LH) with a new one
(Refer to
). Then go to Step 5.
NO : Go to Step 4.
00DB076A
MB991910
DATA LINK
CONNECTOR
MB991824
MB991827
SRS AIR BAG DIAGNOSIS
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-89
STEP 4. Check the harness wires for open circuit or short
circuit between SRS-ECU connector C-121 (terminal No.48
and 47) and front impact sensor (LH) connector A-23
(terminal No.1 and 2).
Q: Are the harness wires between SRS-ECU connector
C-121 (terminal No.48 and 47) 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 B1418 or B1419
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 B1418 or B1419 set?
YES : Return to Step 1.
NO : The procedure is complete.
AC305210
CONNECTOR: A-23
AT
A-23 (Y)
HARNESS SIDE
24DB062A
CONNECTOR: C-121
C-121 (Y)
SRS-ECU
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
C-121
INSTRUMENT
HARNESS
CONNECTOR
(REAR VIEW)
00DB076A
MB991910
DATA LINK
CONNECTOR
MB991824
MB991827
SRS AIR BAG DIAGNOSIS
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-90
DTC B1420: Side-Airbag Module (RH) (Squib) System Fault 1 (Short Circuit between Terminals of the
Squib Circuit)
CAUTION
If DTC B1420 is set in the combination meter,
always diagnose the CAN bus lines.
.
CIRCUIT 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.
.
DTC SET CONDITIONS
This DTC is set if there is abnormal resistance
between the input terminals of the side-airbag mod-
ule (RH) (squib).
.
TROUBLESHOOTING HINTS
• Improper engaged connector or defective short
spring*
• Short between the side-airbag module (RH)
(squib) circuit terminals
• Damaged connector(s)
• Malfunction of the SRS-ECU
• Refer to circuit diagrams GROUP-
• Refer to configuration diagrams GROUP-
NOTE: *: The squib circuit connectors integrate a
"short" spring (which prevents the air bag from
deploying unintentionally due to static electricity by
shorting the positive wire to the ground wire in the
squib circuit when the connectors are disconnected)
(Refer to
). Therefore, if connector D-26 or
D-32 is damaged or improperly engaged, the short
spring may not be released when the connector is
connected.
.
DIAGNOSIS
Required Special Tools:
• MB991958: diagnostic 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)
• MB991865: Dummy resister
• MB991866: Resistor harness
24DB063A
CONNECTOR: D-26
SRS-ECU
63
55
51
69
61
66
58
65
64
5657
68
60
67
59
70
62
53
52 B A
54
D-26 (Y)
D-26 FLOOR
HARNESS
CONNECTOR
(REAR VIEW)
AC307779
D-32 (R)
AC
CONNECTOR : D-32
SRS AIR BAG DIAGNOSIS
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-91
STEP 1. Using diagnostic tool MB991958, diagnose the
CAN bus line.
CAUTION
To prevent damage to diagnostic tool MB991958, always
turn the ignition switch to the "LOCK" (OFF) position
before connecting or disconnecting diagnostic tool
MB991958.
(1) Connect diagnostic tool MB991958. Refer to "How to
connect the diagnostic tool
."
(2) Turn the ignition switch to "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?
YES : Go to Step 2
NO : Repair the CAN bus lines (Refer to GROUP 54C,
Diagnosis ).
STEP 2. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to "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 ).
00DB076A
MB991910
DATA LINK
CONNECTOR
MB991824
MB991827
00DB076A
MB991910
DATA LINK
CONNECTOR
MB991824
MB991827
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