Mitsubishi 380. Manual — part 806
SRS AIR BAG DIAGNOSIS
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-148
DTC B1438: Side Impact Sensor (LH) (Squib) for Power Supply Circuit
DTC B1439: Side Impact Sensor (LH) (Squib) for Communication System
CAUTION
If DTC B1438 or B1439 is set in the SRS-ECU,
always diagnose the CAN main bus line.
.
CIRCUIT OPERATION
The side 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 side-air-
bags should be deployed, it sends a fire signal to the
SRS-ECU to deploy the side-airbags. In addition, the
CPU diagnoses the internal components of the side
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
side impact sensor (LH) and the SRS-ECU is not
possible or faulty.
.
TROUBLESHOOTING HINTS
• Damaged wiring harnesses or connectors
• Malfunction of the side impact sensor (LH)
• Malfunction of the SRS-ECU
• Refer to circuit diagrams GROUP-
• Refer to configuration diagrams GROUP-
.
24DB064A
CONNECTOR: D-27
SRS-ECU
D-27 (Y)
A
B
18
10
15
7
13
5
14
6
16
8
17
9
19
11
20
12
1 2
3 4
D-27 Floor
harness
connector
(rear view)
AC305250
CONNECTOR: D-20
AI
FRONT SEAT BELT
SRS AIR BAG DIAGNOSIS
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-149
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)
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 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,
Diagnosis ).
00DB076A
MB991910
DATA LINK
CONNECTOR
MB991824
MB991827
SRS AIR BAG DIAGNOSIS
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-150
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
diagnostic tool MB991958, read the diagnostic trouble
code.)
Check the side impact sensor (LH).
(1) Disconnect the negative battery terminal.
(2) Replace the side impact sensor (LH) with the side 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 B1428 or B1429 set?
YES : Replace the side 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
00DB076A
MB991910
DATA LINK
CONNECTOR
MB991824
MB991827
SRS AIR BAG DIAGNOSIS
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-151
STEP 4. Check the harness wires for open circuit or short
circuit between SRS-ECU connector D-27 (terminal No.19
and 20) and side impact sensor (LH) connector D-20
(terminal No.1 and 2).
Q: Are the harness wires between SRS-ECU connector
D-27 (terminal No.19 and 20) and side impact sensor
(LH) connector D-20 (terminal No.1 and 2) in good
condition?
YES : Erase the diagnostic trouble code memory, and check
the diagnostic trouble code. If DTC B1438 or B1439
sets, replace the SRS-ECU (Refer to
).
Then go to Step 5.
NO : Replace the harness wires between SRS-ECU
connector D-27 and side impact sensor (LH)
connector D-20. 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 B1438 or B1439 set?
YES : Return to Step 1.
NO : The procedure is complete.
AC305250
CONNECTOR: D-20
AJ
FRONT SEAT BELT
HARNESS SIDE
CONNECTOR
(REAR VIEW)
2
1
24DB064A
CONNECTOR: D-27
SRS-ECU
D-27 (Y)
A
B
18
10
15
7
13
5
14
6
16
8
17
9
19
11
20
12
1 2
3 4
D-27 Floor
harness
connector
(rear view)
00DB076A
MB991910
DATA LINK
CONNECTOR
MB991824
MB991827
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