DTC 68

Passenger's Seat Belt Pre-Tensioner (Squib) System Fault for Power Supply Circuit (short-circuited to Power Supply)

Passenger's (Front) Seat Belt Pre-tensioner (Squib):

Connector:

CIRCUIT OPERATION
- If front air bag analog G-sensor and front air bag safing G-sensor inside the SRS-ECU sense a predetermined collision energy simultaneously during a frontal collision, the SRS-ECU sends igniting signal to the pre-tensioner, causing the pre-tensioner to operate.

DTC SET CONDITIONS
- These DTC are output if there is abnormal resistance between the input terminals of the passenger's seat belt pre-tensioner (squib).

TROUBLESHOOTING HINTS
- Damaged wiring harnesses or connectors
- Short to the power supply in the passenger's seat belt pre-tensioner (squib) harness
- Malfunction of the SRS-ECU

DIAGNOSIS

Required Special Tools:
- MB991502: Scan Tool (MUT-II)
- MB991865: Dummy resister
- MB991866: Resister harness




STEP 1. Check the passenger's seat belt pre-tensioner.
1. 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.

2. Disconnect the passenger's seat belt pre-tensioner connector D-03, and insert special tool MB991866 into the harness side connector by backprobing.
3. Connect the negative battery terminal.
4. Erase DTC memory, and then recheck the DTC.

Q: Is DTC 68 output?

YES: Go to Step 2.
NO: Replace the passenger's seat belt pre-tensioner. Then go to Step 4.

Connector:

STEP 2. Check the harness for short circuit to power supply between the SRS-ECU and the passenger's seat belt pre-tensioner.
1. Disconnect SRS-ECU connector C-13.
2. Disconnect passenger's seat belt pre-tensioner connector D-03.
3. Turn the ignition switch to the "ON" position.
4. Measure at the wiring harness side.

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




5. Measure the voltage between terminals 29, 30 and body ground
- Voltage should be 0 volt.

Q: Is the circuit normal?

YES: Erase the DTC memory, and recheck if any DTC sets. If DTC 68 sets, replace the SRS-ECU. Then go to step 4.
NO: Go to Step 3.

Connector:

STEP 3. Check the harness wires for short circuit to power supply between SRS-ECU connector C-13 and passenger's seat belt pre-tensioner connector D-03.

NOTE: After inspecting intermediate connector C-112 inspect the wiring harness.

If the intermediate connector C-112 is damaged, repair or replace it. Refer to Harness Connector Inspection.

Go to Step 4.

Q: Are the harness wires between SRS-ECU connector C-13 and passenger's seat belt pre-tensioner connector D-03 in good condition?

YES: Go to Step 4.
NO: Repair the harness wires between SRS-ECU connector C-13 and passengers seat belt pre-tensioner connector D-03. Then go to step 4.

STEP 4. Check for DTC.

Q: Is DTC 68 output?

YES: Return to step 1.
NO: This diagnosis is complete. (If no malfunctions are not found in all steps, an intermittent malfunction is suspected. Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction.)