Code No.B1476: IG1 Power Supply Circuit System (Fuse No.2 Circuit)
Code No.B1477: IG1 Power Supply Circuit System (Fuse No.3
Circuit)
| caution |
If diagnosis code B1476 <Fuse
No.2> or B1477 <Fuse No.3> is set in the
combination meter, always diagnose the CAN bus
lines.
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OPERATION
- The SRS-ECU is powered from the ignition switch (IG1).
- The SRS-ECU power is supplied from two circuits. Even if one
circuit is shut off, the air bag can inflate.
DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set if
the voltage between the IG1 terminals (fuse No.2 circuit or fuse No.3
circuit) and earth is lower than a predetermined value for a continuous
period of 5 second or more. However, if the system returns to normal
condition, the warning lamp will be go out. (The diagnosis code is not
erased.)
PROBABLE CAUSES
- Damaged wiring harnesses or connectors
- Malfunction of the SRS-ECU
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STEP 1. M.U.T.-III CAN bus diagnostics
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Use the M.U.T.-III to diagnose the
CAN bus lines.
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Q.
Is the check result normal?
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 Go to Step 2
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 Repair the CAN bus
line (Refer to GROUP 54F, Diagnosis  ).
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STEP 2. Check whether the diagnosis code is
reset.
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Check again if the diagnosis code
is set.
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(1)Erase the diagnosis code.
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(2)Ignition: LOCK (OFF) position to ON
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(3)On completion, check that the diagnosis code is
not reset.
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Q.
Is the diagnosis code set?
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Go to Step
3.
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There is an
intermittent malfunction such as poor engaged connector(s)
or open circuit (Refer to GROUP 00, How to Cope with
Intermittent Malfunction ).
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STEP 3. Check junction block fuse number 2
<B1476> or 3
<B1477>.
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Q.
Is the fuse burned out?
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Go to Step 6
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Go to Step 4
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STEP 4. Check the power supply circuit for open circuit.
Voltage measurement at SRS-ECU connector
C-119.
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(1)Disconnect the negative battery
terminal.
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(2)Disconnect SRS-ECU connector
C-119.
(3)Connect the negative battery
terminal.
(4)Turn the ignition switch to the "ON"
position.
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(5)
| caution |
Do not insert a test probe
into the terminal from its front side directly,
as the connector contact pressure may be
weakened.
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Measure the voltage between C-119 harness side
connector terminal 24 <B1476> or 23
<B1477> and body earth.
OK: 9 V or
more.
Q.
Is the measured voltage within the specified
range?
Erase the
diagnosis connector memory, and check the diagnosis code. If
diagnosis code B1476 or B1477 set, replace the SRS-ECU
(Refer to ). Then go
to Step 10 .
Go to Step
5.
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STEP 5. Connector check: SRS-ECU connector C-119,
ignition switch connector C-307, joint connector C-33
<diagnosis code B1477>, junction block
connector C-202 and C-205.
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Q.
Is the check result normal?
Check the
harness wire for open circuit between SRS-ECU connector
C-119 (terminal No.24 <B1476> or terminal No.23
<B1477>) and the ignition switch connector C-307
(terminal No.2), and repair if necessary. Then go to Step 10
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Repair or
replace it. Then go to Step 10 .
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STEP 6. Check a burned-out fuse.
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(2)Turn the ignition switch to the "ON" position,
wait for at least one minute and then turn the ignition switch
to the "LOCK" (OFF) position.
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Q.
Is the fuse in good condition?
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Go to Step
10 .
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It is
possible that the circuit using fuse No.2
<B1476> or No.3 <B1477> is shorted,
go to Step 7 .
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STEP 7. Check the SRS-ECU power supply circuit for short
circuit to earth. Resistance measurement at the junction
block connector C-205.
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(1)Disconnect junction block
connector C-205, and measure at the wiring harness
side.
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(2)
| caution |
Do not insert a test probe
into the terminal from its front side directly
as the connector contact pressure may be
weakened.
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Measure the resistance between terminal 24
<B1476> or 7 <B1477> and body
earth.
OK: Open circuit
Q.
Is the check result normal?
Check the
other circuit, which flows through fuse No.2
<B1476> or fuse No.3 <B1477>.Then go
to Step 10 .
Go to Step 8
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STEP 8. Check the power supply circuit for short circuit
to earth. Resistance measurement at the SRS-ECU
connector C-119.
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(1)Disconnect SRS-ECU connector
C-119, and measure at the wiring harness side.
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(2)
| caution |
Do not insert a test probe
into the terminal from its front side directly
as the connector contact pressure may be
weakened.
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Measure the resistance between terminal 24
<B1476> or 23 <B1477> and body
earth.
OK: Open circuit
Q.
Does continuity exist?
Erase the
diagnosis code memory, and check the diagnosis code. If
diagnosis code B1476 or B1477 sets, replace the SRS-ECU
(Refer to ). Then go
to Step 10 .
Go to Step 9
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STEP 9. Connector check: SRS-ECU connector C-119, joint
connector C-01 <LHD: B1477>, joint connector
C-33 <RHD: B1477> and junction block
connector C-205.
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Q.
Is the check result normal?
Check the
harness wire for short circuit between SRS-ECU connector
C-119 (terminal No.24 <B1476> or terminal No.23
<B1477>) and junction block connector C-205
(terminal No.24 <B1476> or terminal No.7
<B1477>), and repair if necessary. Then go to
Step 10 .
Repair or
replace it. Then go to Step 10 .
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STEP 10. Check whether the diagnosis code is
reset.
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Q.
Is diagnosis code B1476 or B1477 set?
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Return to
Step 1.
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The procedure is
complete.
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