B1472

DTC B1472: Seat Belt Pre-Tensioner (LH) (Squib) System Fault for Ground Circuit (Short-Circuited to Ground)

Driver's Seat Belt Pre-Tensioner (Squib) Circuit:

CAUTION: DTC B1472 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 pre-tensioner will deploy.

DTC SET CONDITIONS
This DTC is set if there is abnormal resistance between the input terminals of the driver's seat belt pre-tensioner (squib).

TROUBLESHOOTING HITS
- Damaged wiring harnesses or connectors
- Short to the ground in the driver's seat belt pre-tensioner (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
- MB991884: 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 seat belt pre-tensioner. (Using scan tool MB991958, read the diagnostic trouble code.)

1. Disconnect the negative battery terminal.

2. Disconnect driver's seat belt pre-tensioner connector D-16. Use a flat-tipped screwdriver to unlock the locking button at the harness side connector by withdrawing it toward you in two stages, and then disconnect the connector.

3. Connect special tool MB991865 to special tool MB991884.
4. Connect special tool MB991884 to the D-16 harness side connector.
5. Connect the negative battery terminal.
6. Erase diagnostic trouble code memory, and check the diagnostic trouble code.

Q: Is DTC B1472 set?

YES : Go to Step 4.

NO : Replace the driver's seat belt pre-tensioner. Then go to Step 6.

STEP 4. Check the driver's seat belt pre-tensioner circuit. Measure the resistance at the SRS-ECU connector C-122.

1. Disconnect SRS-ECU connector C-122.

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

3. Check for continuity between C-122 harness side connector terminals 7, 8 and body ground.
It should be open circuit.

Q: Does continuity exist?

YES : Go to Step 5.

NO : Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC B1472 sets, replace the SRS-ECU. Then go to Step 6.

STEP 5. Check harness wires for short circuit to ground between SRS-ECU connector C-122 (terminal No.7 and 8) and driver's seat belt pre-tensioner connector D-16 (terminal No.1 and 2).

Q: Are the harness wires between SRS-ECU connector C-122 (terminal No.7 and 8) and driver's seat belt pre-tensioner connector D-16 (terminal No.1 and 2) in good condition?

YES : Go to Step 6.

NO : Replace the harness wires between SRS-ECU connector C-122 and driver's seat belt pre-tensioner connector D-16. Then go to Step 6.

STEP 6. Recheck for diagnostic trouble code.