B1483

DTC B1403: Driver's Air Bag Module (1st Squib) System Fault for Power Supply Circuit (Short-Circuited to Power Supply)

DTC B1483: Driver's Air Bag Module (2nd Squib) System Fault for Power Supply Circuit (Short-Circuited to Power Supply)

Driver's Air Bag Module (1st And 2nd Squib) Circuit:

CAUTION: If DTC B1403[1st squib] or B1483 [2nd squib] is set in the SRS-ECU, always diagnose the CAN main bus line.

CIRCUIT OPERATION
- The SRS-ECU judges how severe a collision is by detecting signals from the front impact sensors and the front air bag analog G-sensor. If the impact is over a predetermined level, the SRS-ECU sends an ignition signal. At this time, if the front air bag safing G-sensor is on, the SRS air bag will inflate.
- The ignition signal is input to the air bag module via the clock spring to inflate the air bag.

DTC SET CONDITIONS
This DTC is set if there is abnormal resistance between the input terminals of the driver's air bag module (squib).

TROUBLESHOOTING HINTS
- Malfunction of the clock spring
- Damaged harness wires and connectors
- Short to the power supply in the driver's air bag module (squib) harness
- Malfunction of the SRS-ECU

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A
- MB991865: Dummy resistor
- MB991866: Resister harness

STEP 1. 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." Scan Tool Connecting
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 Controller Area Network (CAN), 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 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 : Go to Step 3.

NO : There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to General (Body and Chassis), How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions.

STEP 3. Check the driver's air bag module. (Using scan tool MB991958, read the diagnostic trouble code.)

1. Disconnect the negative battery terminal.

2. Slide the outer housing of the driver's air bag module connector C-305 in the arrow direction shown, and disconnect the connector.

3. Connect special tool MB991865 to special tool MB991866.

CAUTION: Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.

4. Insert special tool MB991866 into clock spring side air bag module connector C-305 (terminal No.1 and 2 [1st squib] or terminal No.3 and 4 [2nd squib]) by backprobing.
5. Connect the negative battery terminal.
6. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

Q: Is DTC B1403 [1st squib] or B1483 [2nd squib] set?

YES : Go to Step 4.

NO : Replace the driver's air bag module. Then go to Step 7.

STEP 4. Check the clock spring. (Using scan tool MB991958, read the diagnostic trouble code.)

1. Disconnect the negative battery terminal.

2. Disconnect the clock spring connector C-307.

3. Connect special tool MB991865 to special tool MB991866.

CAUTION: Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.

4. Insert special tool MB991866 into clock spring harness side connector C-307 (terminal No.13 and 14 [1st squib] or terminal No. 11 and 12 [2nd squib]) by backprobing.
5. Connect the negative battery terminal.
6. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

Q: Is DTC B1403 [1st squib] or B1483 [2nd squib] set?

YES : Go to Step 5.

NO : Replace the clock spring. Then go to Step 7.

STEP 5. Check the driver's air bag module circuit. Measure the voltage at the SRS-ECU connector C-123.

1. Disconnect SRS-ECU connector C-123.

DANGER: To prevent the air bag from deploying unintentionally, disconnect the clock spring connector C-307 to short the squib circuit.

2. Disconnect the clock spring connector C-307.
3. 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.

4. Measure the voltage between C-123 harness side connector terminals 36 and 37 [1st squib] or 33 and 34 [2nd squib] and body ground. Voltage should measure 0 volt.

Q: Is the measured voltage 0 volt?

YES : Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC B1403 [1st squib] or B1483 [2nd squib] sets, replace the SRS-ECU. Then go to Step 7.

NO : Go to Step 6.

STEP 6. Check the harness for short circuit to power supply between SRS-ECU connector C-123 (terminal No.36 and 37 [1st squib] or terminal No.33 and 34 [2nd squib]) and clock spring connector C-307 (terminal No.13 and 14 or terminal No. 11 and 12 [2nd squib]).

Q: Are harness wires between the SRS-ECU connector C-123 (terminal No.36 and 37 [1st squib] or terminal No.33 and 34 [2nd squib]) and clock spring connector C-307 (terminal No.13 and 14 or terminal No. 11 and 12 [2nd squib]) in good condition?

YES : Go to Step 7.

NO : Replace the harness wires between SRS-ECU connector C-123 and clock spring connector C-307. Then go to Step 7.

STEP 7. Recheck for diagnostic trouble code.