Code No. B1476
IG1 power supply open circuit (Fuse No. 12 circuit) Code No. B1477 IG1 power supply
open circuit (Fuse No. 18 circuit)
caution
If the diagnosis code B1476
(fuse No. 12) or B1477 (fuse No. 18) is set to SRS-ECU, be sure to diagnose the CAN bus line.
OPERATION
The battery power supply is supplied from the fusible link (34) or (44) to SRS-ECU.
SRS-ECU has two independent battery power supplies circuit (fuse Nos. 12 and 18) having
fuses.
TROUBLE JUDGEMENT
The code is set when the voltage between the IG1 terminal (SRS-ECU terminal No. 21 or
No. 22) and the earth drops below the specified value for 5 seconds continuously. Also, if the
code No. B1476 and B1477 are set at the same time, the battery voltage may have dropped. Therefore,
check the battery first.
PROBABLE CAUSES
Open circuit to power supply circuit
Damaged wiring harness and connectors
Malfunction of SRS-ECU
Malfunction of ETACS-ECU
DIAGNOSIS PROCEDURE
STEP 1. Power supply fuse check.
Q.
Is the fuse in good condition?
Go to Step 3.
Go to Step 2
STEP 2. Fuse open circuit check
(1)Replace the fuse.
(2)Turn the ignition switch to the "ON" position, wait for at least one minute, and
then turn the switch OFF.
(3)Check the fuse.
Q.
Is the fuse in good condition?
Go to Step 3.
Repair the wiring harness between the C-412 ETACS-ECU connector terminal No. 4
and the C-126 SRS-ECU connector terminal No. 21 <fuse Nos. 18>, the C-417 ETACS-ECU connector
terminal No. 5 and the C-126 SRS-ECU connector terminal No. 22 <fuse Nos. 12> and replace
the power supply fuse.
STEP 3. M.U.T.-III CAN bus diagnostics.
Use M.U.T.-III to diagnose the CAN bus lines.
Q.
Is the check result normal?
Go to Step 4.
Repair the CAN bus lines (refer to GROUP 54C -
Troubleshooting ).
Then go to Step 4.
STEP 4. M.U.T.-III other system diagnosis code.
Check if the ETACS diagnosis code is set.
Q.
Is the diagnosis code set?
Diagnose the ETACS (Refer to GROUP 54A -
ETACS -
Troubleshooting ).
Check the input signal of ETACS-ECU ignition switch (IG1) (Refer to GROUP 54A -
Symptom
Procedures ). Then go to Step 5.
STEP 5. Check whether the diagnosis code is reset.
(1)Connect the negative battery terminal.
(2)After erasing the diagnosis code memory, check the diagnosis code again.
(3)Disconnect the negative battery terminal.
Q.
Is diagnosis code No. B1476 or B1477 set?
Go to Step 6.
Intermittent malfunction (Refer to GROUP 00 -
How to Use Troubleshooting/Inspection
Service Points -
How to Cope with Intermittent Malfunction ).
STEP 6. Resistance measurement at the C-126 SRS-ECU connector.
(1)While pushing the part "A" indicated in the figure of the harness side connector, turn
the lock lever to the direction of the arrow to release the lock lever, and disconnect the C-126
SRS-ECU connectors. (2)Take the measurements below at the C-126 wiring harness side connectors.
Continuity between C-126 wiring harness side connector
terminal No. 24 and body earth
OK: Continuity (less than 2 Ω)
Q.
Is the check result normal?
Go to Step 7.
Repair the wiring harness between the C-126 SRS-ECU connector terminal No. 24
and the earth.
STEP 7. Voltage measurement at the C-126 SRS-ECU connector.
(1)Check that the negative battery terminal is disconnected. If the negative battery
terminal is connected, disconnect it.
(2)While pushing the part "A" indicated in the figure of the harness side connector, turn
the lock lever to the direction of the arrow to release the lock lever, and disconnect the C-121
SRS-ECU connector. (3)Connect the negative battery terminal. (4)Ignition switch: ON (5)Take the measurements below at the C-126 harness side connector.
Voltage between terminal No. 21/22 and body
earth
OK: 9 V or more (6)Disconnect the negative battery terminal.
Q.
Is the check result normal?
Go to Step 9.
Go to Step 8.
STEP 8. Resistance measurement at the C-126 SRS-ECU connector.
(1)Check that the negative battery terminal is disconnected. If the negative battery
terminal is connected, disconnect it.
(2)Disconnect the C-412 and C-417ETACS-ECU connector.
(3)While pushing the part "A" indicated in the figure of the harness side connector, turn
the lock lever to the direction of the arrow to release the lock lever, and disconnect the C-126
SRS-ECU connector. (4)
Continuity between C-412 ETACS-ECU connector terminal
No. 4 and C-126 SRS-ECU connector terminal No. 21
Continuity between C-417 ETACS-ECU connector terminal No. 5 and C-126 SRS-ECU connector
terminal No. 22
OK: Continuity (less than 2 Ω)
Q.
Is the check result normal?
Replace the ETACS-ECU (Refer to GROUP 54A -
ETACS-ECU ).
Repair the wiring harness between the C-412 ETACS-ECU connector terminal No. 4,
the C-417 ETACS-ECU connector terminal No. 5 and the C-126 SRS-ECU connector terminal No. 21/22.
STEP 9. Check whether the diagnosis code is reset.
Q.
Is diagnosis code No. B1476 or B1477 set?
Replace SRS-ECU (Refer to ).
Intermittent malfunction (Refer to GROUP 00 -
How to Use Troubleshooting/Inspection
Service Points -
How to Cope with Intermittent Malfunction ).