DTC 71

Side-Airbag Module (RH) (Squib) System Fault 1 (Short Circuit between Terminals of the Squib Circuit)

Side-Airbag Module (RH) (Squib) Circuit:

CIRCUIT OPERATION
- The SRS-ECU judges how severe a collision is by detecting signals from the left and right side impact sensors. If the impact is over a predetermined level, the SRS-ECU outputs an ignition signal. At this time, if the side air bag safing G-sensor is on, the SRS air bag will inflate.
- The ignition signal is input to the air bag module to inflate the air bag.

DTC SET CONDITIONS
- These DTC are output if there is abnormal resistance between the input terminals of the side-airbag module (RH) (squib).

TROUBLESHOOTING HINTS
- Improper engaged connector or defective short bar*
- Short between the side-airbag module (RH) (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-27 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

STEP 1. Check the DTC.

Q: Is DTC 34 output?

YES: Go to Step 2.
NO: Go to Step 3.




STEP 2. Check 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.







STEP 3. Check SRS-ECU connector C-13 and side-airbag module (RH) connector D-27.
1. Disconnect connectors C-13 and D-27, and then reconnect them.
2. Connect the negative battery terminal.
3. Erase the DTC memory, and then recheck the DTC.

Q: Is DTC 71 output?

YES: Go to Step 4.
NO: The inspection is complete. It is assumed that DTC 71 set as connector C-13 or D-27 was engaged improperly.




STEP 4. Check the side-airbag module.
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 side-airbag module (RH) connector D-27, and insert special tool MB991866 into the harness side connector by backprobing.
3. Connect the negative battery terminal.
4. Erase the DTC memory, and then recheck the DTC.

Q: Is DTC 71 output

YES: Go to Step 5.
NO: Replace the seat back assembly of the front seat (RH). Refer to Front Seat. Then go to Step 7.

STEP 5. Check the harness for short circuit between SRS-ECU and the side-airbag module (RH).




1. Disconnect SRS-ECU connector C-13.






CAUTION: To release the short bar in the SRS-ECU connector, disconnect connector D-27 to short the squib circuit.

2. Disconnect side-airbag module connector D-27.






CAUTION: Insert an insulator such as a cable tie to a depth of 4 mm (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 23, 24 and the short bar to release the short bar.
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. Check the continuity between terminals 23 and 24. There should be open circuit.

Q: Is the continuity normal?

YES: Erase the DTC memory, and recheck if any DTC sets. If DTC 71 sets, replace the SRS-ECU. Then go to Step 7.
NO: Go to Step 6.







STEP 6. Check the harness wires for short circuit between SRS-ECU connector C-13 and side-airbag module (RH) connector D-27

Q: Are the harness wires between SRS-ECU connector C-13 and side-airbag module (RH) connector D-27 in good condition?

YES: Go to Step 7.
NO: Repair the harness wires between SRS-ECU connector C-13 and side-airbag module connector D-27. Then go to Step 7.

STEP 7. Check for DTC.

Q: Is DTC 71 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.)