Code No. B1476 IG1 power supply open circuit (Fuse No. 15 circuit)
Code No. B1477 IG1 power supply open circuit (Fuse No. 21 circuit)
caution |
If diagnosis code B1476 (fuse No. 15) or B1477 (fuse No. 21) is set in the SRS-ECU, be sure to diagnose the CAN bus line.
|
|
SRS-ECU has two independent battery power supplies circuit (fuse Nos. 15 and 21) having fuses.
|
|
The code is set when the voltage between the IG1 terminal (SRS-ECU terminal IG1A or No. IG1B) 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.
|
|
- Open circuit to power supply circuit
- Damaged wiring harness and connectors
- Malfunction of SRS-ECU
- Malfunction of ETACS-ECU
|
|
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
|
|
(2)Turn the ignition switch to the "ON" position, wait for at least one minute, and then turn the switch OFF.
|
|
Q.
Is the fuse in good condition?
|
|
Go to Step 3.
|
|
|
|
Repair the wiring harness IG1A line between the junction block connector and the SRS-ECU connector <fuse No. 15>, IG1B line between the junction block connector and the SRS-ECU connector <fuse No. 21> 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 - Check Trouble by Using The Input Signal Check ). Then go to Step 5
.
|
|
|
|
STEP 5. Check whether the diagnosis code is set again.
|
|
(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 SRS-ECU connector.
|
|
(1)Disconnect the SRS-ECU connectors.
|
|
(2)Take the measurements below at the wiring harness side connectors.
- Continuity GND1 line between wiring harness side connector and body earth
OK: Continuity (less than 2 Ω)
|
|
Q.
Is the check result normal?
|
|
Go to Step 7.
|
|
|
|
Repair the wiring harness GND1 line between the SRS-ECU connector and the body earth.
|
|
|
|
STEP 7. Voltage measurement at the SRS-ECU connector (IG1A, IG1B line).
|
|
(1)Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.
|
|
(2)Disconnect the SRS-ECU connector.
|
|
(3)Connect the negative battery terminal.
|
|
(5)Take the measurements below at the harness side connector.
- Voltage IG1A, IG1B line between SRS-ECU connector 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 SRS-ECU connector.
|
|
(1)Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.
|
|
(2)Disconnect the junction block connector.
|
|
(3)Disconnect the SRS-ECU connector.
|
|
(4)
- Continuity IG1A line between junction block connector and SRS-ECU connector
- Continuity IG1B line between junction block connector and SRS-ECU connector
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 IG1A line between the junction block connector and the SRS-ECU connector, IG1B line between the junction block connector and the SRS-ECU connector.
|
|
|
|
STEP 9. Check whether the diagnosis code is set again.
|
|
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 ).
|
|
|