Mitsubishi 380. Manual — part 818
SRS AIR BAG DIAGNOSIS
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-196
STEP 5. Check harness wires for short circuit to ground
between SRS-ECU connector D-27 (terminal No.7 and 8)
and passenger's seat belt pre-tensioner connector D-21
(terminal No.1 and 2).
Q: Are the harness wires between SRS-ECU connector
D-27 (terminal No.7 and 8) and passenger's seat belt
pre-tensioner connector D-21 (terminal No.1 and 2) in
good condition?
YES : Go to Step 6.
NO : Replace the harness wires between SRS-ECU
connector D-27 and passenger's seat belt
pre-tensioner connector D-26. Then go to Step 6.
STEP 6. 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 B1473 set?
YES : Return to Step 1.
NO : The procedure is complete.
AC306920AC
CONNECTOR: D-21
D-21 (B)
FOWARD
CENTER
PILLAR
HARNESS SIDE
CONNECTOR
(FRONT 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
SRS AIR BAG DIAGNOSIS
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-197
DTC B1476: IG1 Power Supply Circuit System (Fuse No.18 Circuit) DTC B1477: IG1 Power Supply
Circuit System (Fuse No.19 Circuit)
CAUTION
If DTC B1476 <Fuse No.18> or B1477 <Fuse
No.19> is set in the combination meter, always
diagnose the CAN bus lines.
.
CIRCUIT OPERATION
• The SRS-ECU is powered from the ignition
switch (IG1).
• The SRS-ECU power is supplied from two cir-
cuits. Even if one circuit is shut off, the air bag
can inflate.
.
DTC SET CONDITIONS
This DTC is set if the voltage between the IG1 termi-
nals (fuse No.18 circuit or fuse No.19 circuit) and
ground is lower than a predetermined value for a
continuous period of five second or more. However, if
the vehicle condition returns to normal, DTC number
B1476 <Fuse No.18> or B1477 <Fuse No.19> will be
automatically erased, and the SRS warning light will
switch off.
.
TROUBLESHOOTING HINTS
• Damaged wiring harnesses or connectors
• Malfunction of the SRS-ECU
• Refer to circuit diagrams GROUP-
• Refer to configuration diagrams GROUP-
.
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)
• MB991223 (MB991222): Harness set (Probe)
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)
SRS AIR BAG DIAGNOSIS
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-198
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 ).
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
SRS AIR BAG DIAGNOSIS
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-199
STEP 3. Check junction block fuse number 18 <DTC
B1476> or 19 <DTC B1477>.
Q: Is the fuse burned out?
YES : Go to Step 6.
NO : Go to Step 4.
STEP 4. Check the power supply circuit for open circuit.
Measure the voltage at SRS-ECU connector C-121.
(1) Disconnect the negative battery terminal.
(2) Disconnect SRS-ECU connector C-121.
(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 C-121 harness side
connector terminal 23 <DTC B1476> or 24 <DTC B1477>
and body ground.
Voltage should measure 9 volts or more.
Q: Is the measured voltage within the specified range?
YES : Erase the diagnosis connector memory, and check
the diagnostic trouble code. If DTC B1476 or B1477
set, replace the SRS-ECU (Refer to
).
Then go to Step 10.
NO : Go to Step 5.
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)
AC308202
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 HARNESS SIDE
CONNECTOR (REAR VIEW)
AB
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