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DTC 26

Driver's Seat Belt Pre-Tensioner (Squib) System Fault 1 (Short Circuit between Terminals of 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 side seat belt pre-tensioner (squib).

TROUBLESHOOTING HINTS
- Improper engaged connector or defective short bar*
- Short circuit between the driver's seat belt pre-tensioner (squib) circuit terminals
- Damaged connector(s)
- Malfunction of the SRS-ECU

NOTE: *: The squib circuit connectors integrate a "short" bar (which prevents the air bag from deploying unintentionally due to static electricity by shorting the positive wire to the ground wire in the squib circuit when the connectors are disconnected). Therefore, if connector C-13 or D-16 is damaged or improperly engaged, the short bar may not be released when the connector is connected.

DIAGNOSIS

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

STEP 1. Check the diagnostic trouble code.

Q: Is DTC 34 set?

YES: Go to Step 2.

NO: Go to Step 3.




STEP 2. Check the SRS-ECU connector C-13.

Q: Is the connector correctly engaged?

YES: Go to Step 3.

NO: Engage the connector correctly. Then go to Step 7.




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







STEP 3. Check SRS-ECU connector C-13 and driver's seat belt pre-tensioner connector D-16.

1. Disconnect the negative battery terminal.
2. Disconnect connectors C-13 and D-16, and then reconnect them. For connector D-16, use a flat-tipped screwdriver to pull out the locking button at the harness connector, and then disconnect the connector.
3. Connector the negative battery terminal.
4. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

Q: Is DTC 26 set?

YES: Go to Step 4.

NO: The procedure is complete. It is assumed that DTC 26 set as connector C-13 or D-16 was engaged improperly.

STEP 4. 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 driver's seat belt pre-tensioner connector D-16. Use a flat-tipped screwdriver to pull out the locking button at the harness connector, and then disconnect the connector.




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 diagnostic trouble code memory, and check the diagnostic trouble code.

Q: Is DTC 26 set?

YES: Go to Step 5.

NO: Replace the driver's seat belt pre-tensioner. Then go to Step 7.

STEP 5. Check the driver s seat belt pre-tensioner circuit at the SRS-ECU connector C-13.




1. Disconnect SRS-ECU connector C-13.

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









DANGER: To prevents the air bag from deploying unintentionally, disconnect the driver s seat belt pre-tensioner connector D-16 to short the squib circuit.

2. Disconnect driver's seat belt pre-tensioner connector D-16. Use a flat-tipped screwdriver to pull out the locking button at the harness connector, and then disconnect the connector.






CAUTION: Insert an insulator such as a cable tie to a depth of 4mm (0.16 inch) or more, otherwise the short bar will not be released.

3. Insert a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) thick] between terminals 29, 30 and the short bar to release the short bar.






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

4. Check for continuity between terminals 29 and 30. It should be open circuit.

Q: Does continuity exist?

YES: Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC 26 sets, replace the SRS-ECU. Then go to Step 7.

NO: Go to Step 6.




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







STEP 6. Check the harness for short circuit between SRS-ECU connector C-13 (terminal No.29 and 30) and driver s seat belt pre-tensioner connector D-16 (terminal No.1 and 2).

NOTE: After inspecting intermediate connector C-128, inspect the wiring harness.
If the intermediate connector C-128 is damaged, repair or replace it. Refer to Harness Connector Inspection.
Go to Step 7.

Q: Are harness wires between SRS-ECU connector C-13 (terminal No.29 and 30) and driver s seat belt pre-tensioner connector D-16 (terminal No.1 and 2) in good condition?

YES: Go to Step 7.

NO: Repair the harness wires between SRS-ECU connector C-13 and driver s seat belt pre-tensioner connector D-16. Then go to Step 7.

STEP 7. Check the diagnostic trouble code.

Q: Is DTC 26 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)
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