B212C

DTC B212C: Open Circuit To IG1 Power Supply (Fuse No.12 Circuit)
DTC B212D: Open Circuit to IG1 Power Supply (Fuse No.18 Circuit)

IG1 Power Supply Circuit:

CAUTION: If DTC B212C (Fuse No.12) or B212D (Fuse No.18) is set in the SRS-ECU, always diagnose the CAN main bus lines.

CIRCUIT OPERATION
- The SRS-ECU is powered from the fusible link (34).
- The SRS-ECU power is supplied from two circuits. Even if one circuit is shut off, the air bag can inflate.

DTC SET CONDITIONS
This code is set when an open circuit occurs in the power supply circuit to the SRS-ECU (terminal No.61) or in the power supply circuit to the SRS-ECU (terminal No.62).Also, if the code No. B212C and B212D are set at the same time, the battery voltage may have dropped. Therefore, check the battery first.

TROUBLESHOOTING HINTS
- Open circuit to power supply circuit
- Damaged wiring harnesses or connectors
- Malfunction of the SRS-ECU
- Malfunction of ETACS-ECU

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)

STEP 1. Power supply fuse number 12, 18 check

Q: Is the fuse in good condition?

YES : Go to Step 3.

NO : Go to Step 2.

STEP 2. Check for a blown fuse.

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?

YES : Go to Step 3.

NO : Repair the wiring harness between the fusible link (34) and the C-36 SRS-ECU connector terminal No. 61/62, and replace the power supply fuse.

STEP 3. Using scan tool MB991958, diagnose the CAN bus line.







CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

1. Connect scan tool MB991958. Refer to "How to connect the scan tool." How To Connect The Scan Tool (M.U.T.-III)
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 4.

NO : Repair the CAN bus line.

STEP 4. Using scan tool MB991958, diagnose the ETACS.

CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

1. Connect scan tool MB991958. Refer to "How to connect the scan tool." How To Connect The Scan Tool (M.U.T.-III)
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 : Diagnose the ETACS (Refer to ETACS, Diagnosis). Diagnostic Trouble Code Descriptions Then go to Step 9

NO : Check the input signal of ETACS-ECU ignition switch (IG1) (Refer to - ETACS, Symptom procedures). Inspection Procedure 2 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 "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 6.

NO : There is an intermittent malfunction such as poor engaged connector(s) or open circuit.

STEP 6. Resistance measurement at the C-37 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-37 SRS-ECU connectors.







2. Take the measurements below at the C-37 wiring harness side connectors. It should be less than 2 ohms.
- Continuity between C-37 wiring harness side connector terminal No. 17 and body ground

Q: Does continuity exist?

YES : Go to Step 7.

NO : Repair the wiring harness between the C-37 SRS-ECU connector terminal No. 17 and the ground.

STEP 7. Measure the voltage at the C-36 SRS-ECU connector.

1. Disconnect the negative battery terminal.







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-36 SRS-ECU connector.
3. Connect the negative battery terminal.
4. Ignition switch: ON







5. Take the measurements below at the C-36 harness side connector.
- Voltage between terminal No. 61/62 and body ground

OK: 9 V or more

Q: Is the measured voltage within the specified range?

YES : Go to Step 9.

NO : Go to Step 8.

STEP 8. Check the harness for open circuit between SRS-ECU connector C-36 (terminal No.61 and 62) and the ETACS-ECU connector C-313 (terminal No.4 and 2).

1. Disconnect the negative battery terminal.







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-36 SRS-ECU connector.
3. Disconnect the ETACS-ECU connector C-313.







4. Check for continuity between the following terminals. It should be less than 2 ohms.

[Fuse No.12]
- SRS-ECU connector C-36 (terminal No.62) and the ETACS-ECU connector C-313 (terminal No.2)

[Fuse No.18]
- SRS-ECU connector C-36 (terminal No.61) and the ETACS-ECU connector C-313 (terminal No.4)

Q: Does continuity exist?

YES : Replace the ETACS-ECU.

NO : Repair the harness wire between SRS-ECU connector C-36 and the ETACS-ECU connector C-313.

STEP 9. 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 B212C [Fuse No.12 circuit] or B212D [Fuse No.18 circuit] set?

YES : Replace the SRS-ECU.

NO : There is an intermittent malfunction such as poor engaged connector(s) or open circuit.