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Home >> Mitsubishi >> 2008 >> Lancer Evolution L4-2.0L Turbo (4B11T/C) >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> B Code Charts >> B1B1A

B1B1A

DTC B1B1A: Curtain Air Bag Module (LH) (Squib) System (Squib Circuit Open)

Curtain Air Bag Module (Squib) (LH) Circuit (Part 1):




Curtain Air Bag Module (Squib) (LH) Circuit (part 2):






CAUTION: If DTC B1B1A 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 side impact sensors installed on the lower side of the center pillar. If the impact is over a predetermined level, the SRS-ECU sends an ignition signal. At this time, if the side collision safing G-sensor is on, the SRS air bag will inflate.
- The ignition signal is input to the curtain air bag module (LH) to inflate the curtain air bag.

DTC SET CONDITIONS
This DTC is set if there is abnormal resistance between the input terminals of the curtain air bag module (LH) (squib).

TROUBLESHOOTING HINTS
- Open circuit in the curtain air bag module (LH) (squib) circuit
- Improper connector contact
- Malfunction of the SRS-ECU

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A (Vehicles with CAN Communication System)
- MB991865: Dummy resistor
- MB991866: Resister harness
- 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, 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 "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 Cope with Intermittent Malfunction).

STEP 3. Check by dummy resistor connection.

1. Disconnect the negative battery terminal.
2. Disconnect the D-15 intermediate connector (connection between curtain air bag harness and floor harness).




3. Connect special tool MB991865 to special tool MB991866.

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

4. Insert the probe of resistor harness, to which the dummy resistor is installed, from the back of D-15 intermediate connector (floor harness side).
5. Connect the negative battery terminal.
6. After erasing the diagnostic trouble code memory, check the diagnostic trouble code again.
7. Disconnect the negative battery terminal.

Q: Is DTC B1B1A set?

YES: Go to Step 4.

NO: Go to Step 5.

STEP 4. Resistance measurement at the C-36 SRS-ECU connector and the D-15 intermediate connector.

1. Disconnect the negative battery terminal.




2. While pushing the part "A" indicated in the figure of the harness side connector, turn the lock lever to the direction of the arrow to release the lock lever, and disconnect the C-36 SRS-ECU connector.

DANGER: To prevent the air bag from deploying unintentionally, disconnect the intermediate connector D-15 to short the squib circuit.

3. Disconnect the D-15 intermediate connector (connection between curtain air bag harness and floor harness).

CAUTION: The short spring may not be released due to the insufficient insertion. Therefore, insert the insulator for 4 mm (0.6 inch) or more.




4. Insert a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) thick] between terminal 41, 42 and the short spring to release the short spring.






CAUTION: Do not insert a probe into the terminal from D-15 intermediate connector front side directly, as the connector contact pressure may be weakened.

5. Check for continuity between the following terminals. It should be less than 2 ohms.
- SRS-ECU connector C-36 (terminal No.41) and the intermediate connector D-15 (terminal No.1)
- SRS-ECU connector C-36 (terminal No.42) and the intermediate connector D-15 (terminal No.2)

Q: Does continuity exist?

YES: Go to Step 6.

NO: Repair the wiring harness between the C-36 harness side connector terminal No. 41, 42 and the D-15 intermediate connector (floor harness side) terminal No. 1, 2.

STEP 5. Resistance measurement at the D-15 intermediate connector terminal No. 1, 2 and the F-28 curtain air bag module harness side connector terminal No. 1, 2.

1. Disconnect the negative battery terminal.

DANGER: To prevent the air bag from deploying unintentionally, disconnect the curtain air bag module connector F-28 to short the squib circuit.




2. Disconnect curtain air bag module (LH) F-28. 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. Disconnect the D-15 intermediate connector (connection between curtain air bag harness and floor harness).




4. Because the short spring is installed to the D-15 intermediate connector (curtain air bag harness side), insert a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) thick] between terminals 1, 2 and the short spring to release the short spring.




5. Connect special tool MB991884 to the removed F-28 harness side connector.






CAUTION: Do not insert a probe into the terminal from D-15 intermediate connector front side directly, as the connector contact pressure may be weakened.

6. Check for continuity between the following terminals. It should be less than 2 ohms.
- Intermediate connector D-15 (terminal No.1) and resistor harness connector terminal No.2)
- Intermediate connector D-15 (terminal No.2) and resistor harness connector terminal No.1)

Q: Does continuity exist?

YES: Replace the curtain air bag module (squib).

NO: Repair the wiring harness.

STEP 6. 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 DTC B1B1A set?

YES: Replace SRS-ECU.

NO: Intermittent Malfunction (Refer to general (Body and Chassis), How to Use Troubleshooting/Inspection Service Points ? How to Cope with Intermittent Malfunction).
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