B1448

DTC B1448: Side Impact Sensor (Rear) (RH) (Squib) for Power Supply Circuit

DTC B1449: Side Impact Sensor (Rear) (RH) (Squib) for Communication System

Side Impact Sensor (Rear: RH) Circuit:

CAUTION: If DTC B1448 or B1449 is set in the SRS-ECU, always diagnose the CAN main bus line.

CIRCUIT OPERATION
The side impact sensor includes an analog G-sensor and CPU, etc. The CPU monitors the analog G-sensor output signal. If the CPU judges that the curtain air bag should be deployed, it sends a fire signal to the SRS-ECU to deploy the curtain air bag. In addition, the CPU diagnoses the internal components of the side impact sensor. If a malfunction occurs, it requests the SRS-ECU to set a diagnostic trouble code.

DTC SET CONDITIONS
These DTCs are set if communication between the side impact sensor (rear RH) and the SRS-ECU is not possible or communication is faulty.

TROUBLESHOOTING HINTS
- Damaged wiring harnesses or connectors
- Malfunction of the side impact sensor (rear RH)
- Malfunction of the SRS-ECU

DIAGNOSIS

Required Special Tool:
- 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. 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 2.

NO : Repair the CAN bus line.

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.

STEP 3. Check any diagnostic trouble code. (Using scan tool MB991958, read the diagnostic trouble code.)

Check the side impact sensor (rear RH).

1. Disconnect the negative battery terminal.
2. Temporarily replace the side impact sensor (rear RH) with the side impact sensor (rear LH).

3. Connect the negative battery terminal.
4. Erase diagnostic trouble code memory, and check the diagnostic trouble code.

Q: Is DTC B1458 or B1459 set?

YES : Replace the side impact sensor (rear RH) with a new one. Then go to Step 5.

NO : Go to Step 4.

STEP 4. Check the harness wires for open circuit or short circuit between SRS-ECU connector C-120 (terminal No.67 and 68) and side impact sensor (rear RH) connector D-41 (terminal No.1 and 2).

Q: Are the harness wires between SRS-ECU connector C-120 (terminal No.67 and 68) and side impact sensor (rear RH) connector D-41 (terminal No.1 and 2) in good condition?

YES : Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC B1448 or B1449 sets, replace the SRS-ECU. Then go to Step 5.

NO : Replace the harness wires between SRS-ECU connector C-120 and side impact sensor (rear RH) connector D-41. Then go to Step 5.

STEP 5. Recheck for diagnostic trouble code.