DTC 27

Driver's Seat Belt Pre-Tensioner (Squib) System Fault 2 (Open in the Squib Circuit)

Driver's Seat Belt Pre-Tensioner (Squib) Part 1:

Driver's Seat Belt Pre-Tensioner (Squib) Part 2:

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 outputs 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 HINTS
- Improper connector contact
- Open circuit in the driver's seat belt pre-tensioner (squib) circuit
- Malfunction of the SRS-ECU

DIAGNOSIS

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

STEP 1. Check the driver's seat belt pre-tensioner.
1. Disconnect the negative battery terminal.

Driver's Seat Belt Pre-tensioner (Squib) Part 2:

2. Disconnect the driver's seat belt pre-tensioner connector D-16, and insert special tool MB991866 into the harness side connector by backprobing.




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

Q: Is DTC 27 set?

YES: Go to Step 2.

NO: Replace the driver's seat belt pre-tensioner. Then go to Step 3.


STEP 2. Check the harness for open circuit between SRS-ECU connector C-13 (terminal No.29 and 30) and the driver's seat belt pre-tensioner connector D-16 (terminal No.1 and 2).

Driver's Seat Belt Pre-tensioner (Squib) Part 2:

1. Disconnect SRS-ECU connector C-13 and driver's seat belt pre-tensioner connector D-16, and measure at the wiring harness side. For connector D-16, use a flat-tipped screwdriver to pull out the locking button at the harness side connector, and then disconnect the connector.




2. Connect D-16 harness connector to special tool MB991884.






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 the following terminals.
C-13 connector Special tool (MB991884)
30 2
29 1
It should be less than 2 ohms.

Q: Does continuity exist?

YES: Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC 27 sets, replace the SRS-ECU. Then go to Step 3.

NO: Repair harness wires between SRS-ECU connector C-13 and driver's seat belt pre-tensioner connector D-16. Then go to Step 3.

STEP 3. Check the diagnostic trouble code.

Q: Is DTC 27 set?

YES: Return to Step 1.

NO: The procedure is complete. (If no malfunctions are not found in all steps, an intermittent malfunction is suspected. How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction.)