B1547

DTC B1547: Passenger's Front Air Bag Cut Off System

CAUTION: If DTC B1547 is set in the SRS-ECU, always diagnose the CAN main bus line.

DTC SET CONDITIONS
This DTC is set if the following conditions are detected:
- Malfunction of occupant classification-ECU system
- Malfunction of front passenger's seat belt switch system
- Malfunction of front passenger's air bag module system
- Malfunction of SRS-ECU system

TROUBLESHOOTING HINTS
Malfunction of SRS-ECU

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: MUT-III USB Cable
- MB991910: MUT-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." Reading Diagnostic Trouble Codes
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 Diagnosis). Component Tests and General Diagnostics




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 How to Cope with Intermittent Malfunction).




STEP 3. Using scan tool MB991958, read the diagnostic trouble code.

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.

Check that the DTC except B1547 is set.

1. Turn the ignition switch to the "ON" position.
2. Check if the DTC is set.
3. Turn the ignition switch to the "LOOK (OFF)" position.

Q: Is the DTC set?

YES: Carry out the troubleshooting according to a set DTC. Refer to Diagnostic Trouble Code Chart. Diagnostic Trouble Code Descriptions

NO: Go to Step 4.




STEP 4. 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 B1547 set?

YES: Replace the SRS-ECU.

NO: The procedure is complete.